diff --git a/builtin/init.lua b/builtin/init.lua
index 6b27cf76e..4400a19d6 100644
--- a/builtin/init.lua
+++ b/builtin/init.lua
@@ -12,7 +12,7 @@ if core.print then
 	-- Override native print and use
 	-- terminal if that's turned on
 	function print(...)
-		local n, t = select("#", ...), { ... }
+		local n, t = select("#", ...), {...}
 		for i = 1, n do
 			t[i] = tostring(t[i])
 		end
@@ -25,26 +25,26 @@ os.setlocale("C", "numeric")
 minetest = core
 
 -- Load other files
-local scriptdir = core.get_builtin_path()..DIR_DELIM
-local gamepath = scriptdir.."game"..DIR_DELIM
-local commonpath = scriptdir.."common"..DIR_DELIM
-local asyncpath = scriptdir.."async"..DIR_DELIM
+local scriptdir = core.get_builtin_path() .. DIR_DELIM
+local gamepath = scriptdir .. "game" .. DIR_DELIM
+local commonpath = scriptdir .. "common" .. DIR_DELIM
+local asyncpath = scriptdir .. "async" .. DIR_DELIM
 
-dofile(commonpath.."strict.lua")
-dofile(commonpath.."serialize.lua")
-dofile(commonpath.."misc_helpers.lua")
+dofile(commonpath .. "strict.lua")
+dofile(commonpath .. "serialize.lua")
+dofile(commonpath .. "misc_helpers.lua")
 
 if INIT == "game" then
-	dofile(gamepath.."init.lua")
+	dofile(gamepath .. "init.lua")
 elseif INIT == "mainmenu" then
 	local mainmenuscript = core.setting_get("main_menu_script")
 	if mainmenuscript ~= nil and mainmenuscript ~= "" then
 		dofile(mainmenuscript)
 	else
-		dofile(core.get_mainmenu_path()..DIR_DELIM.."init.lua")
+		dofile(core.get_mainmenu_path() .. DIR_DELIM .. "init.lua")
 	end
 elseif INIT == "async" then
-	dofile(asyncpath.."init.lua")
+	dofile(asyncpath .. "init.lua")
 else
 	error(("Unrecognized builtin initialization type %s!"):format(tostring(INIT)))
 end
diff --git a/builtin/mainmenu/init.lua b/builtin/mainmenu/init.lua
index 69536630d..6dd345ff4 100644
--- a/builtin/mainmenu/init.lua
+++ b/builtin/mainmenu/init.lua
@@ -37,23 +37,29 @@ dofile(menupath .. DIR_DELIM .. "common.lua")
 dofile(menupath .. DIR_DELIM .. "gamemgr.lua")
 dofile(menupath .. DIR_DELIM .. "modmgr.lua")
 dofile(menupath .. DIR_DELIM .. "store.lua")
+dofile(menupath .. DIR_DELIM .. "textures.lua")
+
 dofile(menupath .. DIR_DELIM .. "dlg_config_world.lua")
-dofile(menupath .. DIR_DELIM .. "tab_credits.lua")
-dofile(menupath .. DIR_DELIM .. "tab_mods.lua")
-dofile(menupath .. DIR_DELIM .. "tab_settings.lua")
 dofile(menupath .. DIR_DELIM .. "dlg_settings_advanced.lua")
 if PLATFORM ~= "Android" then
 	dofile(menupath .. DIR_DELIM .. "dlg_create_world.lua")
 	dofile(menupath .. DIR_DELIM .. "dlg_delete_mod.lua")
 	dofile(menupath .. DIR_DELIM .. "dlg_delete_world.lua")
 	dofile(menupath .. DIR_DELIM .. "dlg_rename_modpack.lua")
-	dofile(menupath .. DIR_DELIM .. "tab_multiplayer.lua")
-	dofile(menupath .. DIR_DELIM .. "tab_server.lua")
-	dofile(menupath .. DIR_DELIM .. "tab_singleplayer.lua")
-	dofile(menupath .. DIR_DELIM .. "tab_texturepacks.lua")
-	dofile(menupath .. DIR_DELIM .. "textures.lua")
+end
+
+local tabs = {}
+
+tabs.settings = dofile(menupath .. DIR_DELIM .. "tab_settings.lua")
+tabs.mods = dofile(menupath .. DIR_DELIM .. "tab_mods.lua")
+tabs.credits = dofile(menupath .. DIR_DELIM .. "tab_credits.lua")
+if PLATFORM == "Android" then
+	tabs.simple_main = dofile(menupath .. DIR_DELIM .. "tab_simple_main.lua")
 else
-	dofile(menupath .. DIR_DELIM .. "tab_simple_main.lua")
+	tabs.singleplayer = dofile(menupath .. DIR_DELIM .. "tab_singleplayer.lua")
+	tabs.multiplayer = dofile(menupath .. DIR_DELIM .. "tab_multiplayer.lua")
+	tabs.server = dofile(menupath .. DIR_DELIM .. "tab_server.lua")
+	tabs.texturepacks = dofile(menupath .. DIR_DELIM .. "tab_texturepacks.lua")
 end
 
 --------------------------------------------------------------------------------
@@ -69,8 +75,19 @@ local function init_globals()
 	-- Init gamedata
 	gamedata.worldindex = 0
 
+	if PLATFORM == "Android" then
+		local world_list = core.get_worlds()
+		local world_index = table.indexof(world_list, "singleplayerworld")
 
-	if PLATFORM ~= "Android" then
+		if world_index == -1 then
+			core.create_world("singleplayerworld", 1)
+
+			world_list = core.get_worlds()
+			world_index = table.indexof(world_list, "singleplayerworld")
+		end
+
+		gamedata.worldindex = world_index
+	else
 		menudata.worldlist = filterlist.create(
 			core.get_worlds,
 			compare_worlds,
@@ -89,61 +106,34 @@ local function init_globals()
 
 		if not core.setting_get("menu_last_game") then
 			local default_game = core.setting_get("default_game") or "minetest"
-			core.setting_set("menu_last_game", default_game )
+			core.setting_set("menu_last_game", default_game)
 		end
 
 		mm_texture.init()
-	else
-		local world_list = core.get_worlds()
-
-		local found_singleplayerworld = false
-
-		for i,world in pairs(world_list) do
-			if world.name == "singleplayerworld" then
-				found_singleplayerworld = true
-				gamedata.worldindex = i
-				break
-			end
-		end
-
-		if not found_singleplayerworld then
-			core.create_world("singleplayerworld", 1)
-
-			local world_list = core.get_worlds()
-
-			for i,world in pairs(world_list) do
-				if world.name == "singleplayerworld" then
-					gamedata.worldindex = i
-					break
-				end
-			end
-		end
 	end
 
 	-- Create main tabview
-	local tv_main = tabview_create("maintab",{x=12,y=5.2},{x=0,y=0})
-	if PLATFORM ~= "Android" then
-		tv_main:set_autosave_tab(true)
-	end
-	if PLATFORM ~= "Android" then
-		tv_main:add(tab_singleplayer)
-		tv_main:add(tab_multiplayer)
-		tv_main:add(tab_server)
+	local tv_main = tabview_create("maintab", {x = 12, y = 5.2}, {x = 0, y = 0})
+
+	if PLATFORM == "Android" then
+		tv_main:add(tabs.simple_main)
+		tv_main:add(tabs.settings)
 	else
-		tv_main:add(tab_simple_main)
+		tv_main:set_autosave_tab(true)
+		tv_main:add(tabs.singleplayer)
+		tv_main:add(tabs.multiplayer)
+		tv_main:add(tabs.server)
+		tv_main:add(tabs.settings)
+		tv_main:add(tabs.texturepacks)
 	end
-	tv_main:add(tab_settings)
-	if PLATFORM ~= "Android" then
-		tv_main:add(tab_texturepacks)
-	end
-	tv_main:add(tab_mods)
-	tv_main:add(tab_credits)
+
+	tv_main:add(tabs.mods)
+	tv_main:add(tabs.credits)
 
 	tv_main:set_global_event_handler(main_event_handler)
-
 	tv_main:set_fixed_size(false)
 
-	if not (PLATFORM == "Android") then
+	if PLATFORM ~= "Android" then
 		tv_main:set_tab(core.setting_get("maintab_LAST"))
 	end
 	ui.set_default("maintab")
@@ -151,9 +141,9 @@ local function init_globals()
 
 	-- Create modstore ui
 	if PLATFORM == "Android" then
-		modstore.init({x=12, y=6}, 3, 2)
+		modstore.init({x = 12, y = 6}, 3, 2)
 	else
-		modstore.init({x=12, y=8}, 4, 3)
+		modstore.init({x = 12, y = 8}, 4, 3)
 	end
 
 	ui.update()
diff --git a/builtin/mainmenu/init_simple.lua b/builtin/mainmenu/init_simple.lua
index c3891d21c..298bd834e 100644
--- a/builtin/mainmenu/init_simple.lua
+++ b/builtin/mainmenu/init_simple.lua
@@ -1,4 +1,4 @@
 -- helper file to be able to debug the simple menu on PC
 -- without messing around with actual menu code!
-PLATFORM="Android"
+PLATFORM = "Android"
 dofile("builtin/mainmenu/init.lua")
diff --git a/builtin/mainmenu/tab_credits.lua b/builtin/mainmenu/tab_credits.lua
index 5cb730b38..822f64844 100644
--- a/builtin/mainmenu/tab_credits.lua
+++ b/builtin/mainmenu/tab_credits.lua
@@ -69,7 +69,7 @@ local previous_contributors = {
 	"Zefram <zefram@fysh.org>",
 }
 
-tab_credits = {
+return {
 	name = "credits",
 	caption = fgettext("Credits"),
 	cbf_formspec = function(tabview, name, tabdata)
diff --git a/builtin/mainmenu/tab_mods.lua b/builtin/mainmenu/tab_mods.lua
index af758f8df..69027c015 100644
--- a/builtin/mainmenu/tab_mods.lua
+++ b/builtin/mainmenu/tab_mods.lua
@@ -163,7 +163,7 @@ local function handle_buttons(tabview, fields, tabname, tabdata)
 end
 
 --------------------------------------------------------------------------------
-tab_mods = {
+return {
 	name = "mods",
 	caption = fgettext("Mods"),
 	cbf_formspec = get_formspec,
diff --git a/builtin/mainmenu/tab_multiplayer.lua b/builtin/mainmenu/tab_multiplayer.lua
index 2072f8c38..06d8791f0 100644
--- a/builtin/mainmenu/tab_multiplayer.lua
+++ b/builtin/mainmenu/tab_multiplayer.lua
@@ -256,10 +256,10 @@ local function on_change(type,old_tab,new_tab)
 end
 
 --------------------------------------------------------------------------------
-tab_multiplayer = {
+return {
 	name = "multiplayer",
 	caption = fgettext("Client"),
 	cbf_formspec = get_formspec,
 	cbf_button_handler = main_button_handler,
 	on_change = on_change
-	}
+}
diff --git a/builtin/mainmenu/tab_server.lua b/builtin/mainmenu/tab_server.lua
index d08eecc21..6b96825a0 100644
--- a/builtin/mainmenu/tab_server.lua
+++ b/builtin/mainmenu/tab_server.lua
@@ -186,10 +186,10 @@ local function main_button_handler(this, fields, name, tabdata)
 end
 
 --------------------------------------------------------------------------------
-tab_server = {
+return {
 	name = "server",
 	caption = fgettext("Server"),
 	cbf_formspec = get_formspec,
 	cbf_button_handler = main_button_handler,
 	on_change = nil
-	}
+}
diff --git a/builtin/mainmenu/tab_settings.lua b/builtin/mainmenu/tab_settings.lua
index 6285968eb..2649a8a57 100644
--- a/builtin/mainmenu/tab_settings.lua
+++ b/builtin/mainmenu/tab_settings.lua
@@ -384,7 +384,7 @@ local function handle_settings_buttons(this, fields, tabname, tabdata)
 	return ddhandled
 end
 
-tab_settings = {
+return {
 	name = "settings",
 	caption = fgettext("Settings"),
 	cbf_formspec = formspec,
diff --git a/builtin/mainmenu/tab_simple_main.lua b/builtin/mainmenu/tab_simple_main.lua
index 434113b5f..b32418938 100644
--- a/builtin/mainmenu/tab_simple_main.lua
+++ b/builtin/mainmenu/tab_simple_main.lua
@@ -196,10 +196,10 @@ local function on_activate(type,old_tab,new_tab)
 end
 
 --------------------------------------------------------------------------------
-tab_simple_main = {
+return {
 	name = "main",
 	caption = fgettext("Main"),
 	cbf_formspec = get_formspec,
 	cbf_button_handler = main_button_handler,
 	on_change = on_activate
-	}
+}
diff --git a/builtin/mainmenu/tab_singleplayer.lua b/builtin/mainmenu/tab_singleplayer.lua
index a40918af9..05060cbc6 100644
--- a/builtin/mainmenu/tab_singleplayer.lua
+++ b/builtin/mainmenu/tab_singleplayer.lua
@@ -241,10 +241,10 @@ local function on_change(type, old_tab, new_tab)
 end
 
 --------------------------------------------------------------------------------
-tab_singleplayer = {
+return {
 	name = "singleplayer",
 	caption = fgettext("Singleplayer"),
 	cbf_formspec = get_formspec,
 	cbf_button_handler = main_button_handler,
 	on_change = on_change
-	}
+}
diff --git a/builtin/mainmenu/tab_texturepacks.lua b/builtin/mainmenu/tab_texturepacks.lua
index 2b0c77afc..a102fd61d 100644
--- a/builtin/mainmenu/tab_texturepacks.lua
+++ b/builtin/mainmenu/tab_texturepacks.lua
@@ -123,10 +123,10 @@ local function main_button_handler(tabview, fields, name, tabdata)
 end
 
 --------------------------------------------------------------------------------
-tab_texturepacks = {
+return {
 	name = "texturepacks",
 	caption = fgettext("Texturepacks"),
 	cbf_formspec = get_formspec,
 	cbf_button_handler = main_button_handler,
 	on_change = nil
-	}
+}
diff --git a/cmake/Modules/FindNcursesw.cmake b/cmake/Modules/FindNcursesw.cmake
index dcb7cdda8..b8c7f78f2 100644
--- a/cmake/Modules/FindNcursesw.cmake
+++ b/cmake/Modules/FindNcursesw.cmake
@@ -147,6 +147,21 @@ if(CURSES_USE_NCURSESW)
       set(CURSES_HAVE_NCURSESW_CURSES_H "CURSES_HAVE_NCURSESW_CURSES_H-NOTFOUND")
     endif()
   endif()
+  if(NOT DEFINED CURSES_HAVE_NCURSES_H)
+    if(EXISTS "${CURSES_INCLUDE_PATH}/ncurses.h")
+      set(CURSES_HAVE_NCURSES_H "${CURSES_INCLUDE_PATH}/ncurses.h")
+    else()
+      set(CURSES_HAVE_NCURSES_H "CURSES_HAVE_NCURSES_H-NOTFOUND")
+    endif()
+  endif()
+  if(NOT DEFINED CURSES_HAVE_CURSES_H)
+    if(EXISTS "${CURSES_INCLUDE_PATH}/curses.h")
+      set(CURSES_HAVE_CURSES_H "${CURSES_INCLUDE_PATH}/curses.h")
+    else()
+      set(CURSES_HAVE_CURSES_H "CURSES_HAVE_CURSES_H-NOTFOUND")
+    endif()
+  endif()
+
 
   find_library(CURSES_FORM_LIBRARY form HINTS "${_cursesLibDir}"
     DOC "Path to libform.so or .lib or .a")
diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index 4a4e345a9..a03a95d9e 100644
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -361,9 +361,9 @@ Colorize the textures with the given color.
 it is an int, then it specifies how far to interpolate between the
 colors where 0 is only the texture color and 255 is only `<color>`. If
 omitted, the alpha of `<color>` will be used as the ratio.  If it is
-the word "`alpha`", then the alpha of the color will be multiplied with
-the alpha of the texture with the RGB of the color replacing the RGB of
-the texture.
+the word "`alpha`", then each texture pixel will contain the RGB of
+`<color>` and the alpha of `<color>` multiplied by the alpha of the
+texture pixel.
 
 Sounds
 ------
diff --git a/src/client/tile.cpp b/src/client/tile.cpp
index f0c0b4e9e..e6668063c 100644
--- a/src/client/tile.cpp
+++ b/src/client/tile.cpp
@@ -553,16 +553,11 @@ static void blit_with_alpha(video::IImage *src, video::IImage *dst,
 static void blit_with_alpha_overlay(video::IImage *src, video::IImage *dst,
 		v2s32 src_pos, v2s32 dst_pos, v2u32 size);
 
-// Like blit_with_alpha overlay, but uses an int to calculate the ratio
-// and modifies any destination pixels that are not fully transparent
-static void blit_with_interpolate_overlay(video::IImage *src, video::IImage *dst,
-		v2s32 src_pos, v2s32 dst_pos, v2u32 size, int ratio);
-
 // Apply a color to an image.  Uses an int (0-255) to calculate the ratio.
 // If the ratio is 255 or -1 and keep_alpha is true, then it multiples the
 // color alpha with the destination alpha.
 // Otherwise, any pixels that are not fully transparent get the color alpha.
-static void apply_colorize(video::IImage *dst, v2s32 dst_pos, v2u32 size,
+static void apply_colorize(video::IImage *dst, v2u32 dst_pos, v2u32 size,
 		video::SColor color, int ratio, bool keep_alpha);
 
 // Apply a mask to an image
@@ -1656,7 +1651,7 @@ bool TextureSource::generateImagePart(std::string part_of_name,
 			else if (ratio_str == "alpha")
 				keep_alpha = true;
 
-			apply_colorize(baseimg, v2s32(0, 0), baseimg->getDimension(), color, ratio, keep_alpha);
+			apply_colorize(baseimg, v2u32(0, 0), baseimg->getDimension(), color, ratio, keep_alpha);
 		}
 		else if (str_starts_with(part_of_name, "[applyfiltersformesh"))
 		{
@@ -1753,6 +1748,9 @@ static void blit_with_alpha_overlay(video::IImage *src, video::IImage *dst,
 	}
 }
 
+// This function has been disabled because it is currently unused.
+// Feel free to re-enable if you find it handy.
+#if 0
 /*
 	Draw an image on top of an another one, using the specified ratio
 	modify all partially-opaque pixels in the destination.
@@ -1779,11 +1777,12 @@ static void blit_with_interpolate_overlay(video::IImage *src, video::IImage *dst
 		}
 	}
 }
+#endif
 
 /*
 	Apply color to destination
 */
-static void apply_colorize(video::IImage *dst, v2s32 dst_pos, v2u32 size,
+static void apply_colorize(video::IImage *dst, v2u32 dst_pos, v2u32 size,
 		video::SColor color, int ratio, bool keep_alpha)
 {
 	u32 alpha = color.getAlpha();
@@ -1791,8 +1790,8 @@ static void apply_colorize(video::IImage *dst, v2s32 dst_pos, v2u32 size,
 	if ((ratio == -1 && alpha == 255) || ratio == 255) { // full replacement of color
 		if (keep_alpha) { // replace the color with alpha = dest alpha * color alpha
 			dst_c = color;
-			for (s32 y = dst_pos.Y; y < dst_pos.Y + size.Y; y++)
-			for (s32 x = dst_pos.X; x < dst_pos.X + size.X; x++) {
+			for (u32 y = dst_pos.Y; y < dst_pos.Y + size.Y; y++)
+			for (u32 x = dst_pos.X; x < dst_pos.X + size.X; x++) {
 				u32 dst_alpha = dst->getPixel(x, y).getAlpha();
 				if (dst_alpha > 0) {
 					dst_c.setAlpha(dst_alpha * alpha / 255);
@@ -1800,15 +1799,15 @@ static void apply_colorize(video::IImage *dst, v2s32 dst_pos, v2u32 size,
 				}
 			}
 		} else { // replace the color including the alpha
-			for (s32 y = dst_pos.Y; y < dst_pos.Y + size.Y; y++)
-			for (s32 x = dst_pos.X; x < dst_pos.X + size.X; x++)
+			for (u32 y = dst_pos.Y; y < dst_pos.Y + size.Y; y++)
+			for (u32 x = dst_pos.X; x < dst_pos.X + size.X; x++)
 				if (dst->getPixel(x, y).getAlpha() > 0)
 					dst->setPixel(x, y, color);
 		}
 	} else {  // interpolate between the color and destination
 		float interp = (ratio == -1 ? color.getAlpha() / 255.0f : ratio / 255.0f);
-		for (s32 y = dst_pos.Y; y < dst_pos.Y + size.Y; y++)
-		for (s32 x = dst_pos.X; x < dst_pos.X + size.X; x++) {
+		for (u32 y = dst_pos.Y; y < dst_pos.Y + size.Y; y++)
+		for (u32 x = dst_pos.X; x < dst_pos.X + size.X; x++) {
 			dst_c = dst->getPixel(x, y);
 			if (dst_c.getAlpha() > 0) {
 				dst_c = color.getInterpolated(dst_c, interp);
diff --git a/src/collision.cpp b/src/collision.cpp
index 16db3310c..74c0c25c3 100644
--- a/src/collision.cpp
+++ b/src/collision.cpp
@@ -332,8 +332,10 @@ collisionMoveResult collisionMoveSimple(Environment *env, IGameDef *gamedef,
 
 	// Do not move if world has not loaded yet, since custom node boxes
 	// are not available for collision detection.
-	if (!any_position_valid)
+	if (!any_position_valid) {
+		*speed_f = v3f(0, 0, 0);
 		return result;
+	}
 
 	} // tt2
 
diff --git a/src/mapgen_flat.cpp b/src/mapgen_flat.cpp
index 7a5302df0..ecfbe49ba 100644
--- a/src/mapgen_flat.cpp
+++ b/src/mapgen_flat.cpp
@@ -58,7 +58,8 @@ MapgenFlat::MapgenFlat(int mapgenid, MapgenParams *params, EmergeManager *emerge
 	//// amount of elements to skip for the next index
 	//// for noise/height/biome maps (not vmanip)
 	this->ystride = csize.X;
-	this->zstride = csize.X * (csize.Y + 2);
+	// 1-down overgeneration
+	this->zstride_1d = csize.X * (csize.Y + 1);
 
 	this->biomemap        = new u8[csize.X * csize.Z];
 	this->heightmap       = new s16[csize.X * csize.Z];
@@ -80,8 +81,9 @@ MapgenFlat::MapgenFlat(int mapgenid, MapgenParams *params, EmergeManager *emerge
 	noise_filler_depth = new Noise(&sp->np_filler_depth, seed, csize.X, csize.Z);
 
 	//// 3D noise
-	noise_cave1 = new Noise(&sp->np_cave1, seed, csize.X, csize.Y + 2, csize.Z);
-	noise_cave2 = new Noise(&sp->np_cave2, seed, csize.X, csize.Y + 2, csize.Z);
+	// 1-down overgeneraion
+	noise_cave1 = new Noise(&sp->np_cave1, seed, csize.X, csize.Y + 1, csize.Z);
+	noise_cave2 = new Noise(&sp->np_cave2, seed, csize.X, csize.Y + 1, csize.Z);
 
 	//// Biome noise
 	noise_heat           = new Noise(&params->np_biome_heat,           seed, csize.X, csize.Z);
@@ -566,19 +568,19 @@ void MapgenFlat::generateCaves(s16 max_stone_y)
 	for (s16 x = node_min.X; x <= node_max.X; x++, index2d++) {
 		bool column_is_open = false;  // Is column open to overground
 		bool is_tunnel = false;  // Is tunnel or tunnel floor
-		u32 vi = vm->m_area.index(x, node_max.Y + 1, z);
-		u32 index3d = (z - node_min.Z) * zstride + (csize.Y + 1) * ystride +
+		u32 vi = vm->m_area.index(x, node_max.Y, z);
+		u32 index3d = (z - node_min.Z) * zstride_1d + csize.Y * ystride +
 			(x - node_min.X);
 		// Biome of column
 		Biome *biome = (Biome *)bmgr->getRaw(biomemap[index2d]);
 
-		for (s16 y = node_max.Y + 1; y >= node_min.Y - 1;
-				y--, index3d -= ystride, vm->m_area.add_y(em, vi, -1)) {
-			// Don't excavate the overgenerated stone at node_max.Y + 1,
-			// this creates a 'roof' over the tunnel, preventing light in
-			// tunnels at mapchunk borders when generating mapchunks upwards.
-			if (y > node_max.Y)
-				continue;
+		// Don't excavate the overgenerated stone at node_max.Y + 1,
+		// this creates a 'roof' over the tunnel, preventing light in
+		// tunnels at mapchunk borders when generating mapchunks upwards.
+		// This 'roof' is removed when the mapchunk above is generated.
+		for (s16 y = node_max.Y; y >= node_min.Y - 1; y--,
+				index3d -= ystride,
+				vm->m_area.add_y(em, vi, -1)) {
 
 			content_t c = vm->m_data[vi].getContent();
 			if (c == CONTENT_AIR || c == biome->c_water_top ||
diff --git a/src/mapgen_flat.h b/src/mapgen_flat.h
index 282e42975..8ddfe708f 100644
--- a/src/mapgen_flat.h
+++ b/src/mapgen_flat.h
@@ -60,7 +60,7 @@ public:
 	BiomeManager *bmgr;
 
 	int ystride;
-	int zstride;
+	int zstride_1d;
 	u32 spflags;
 
 	v3s16 node_min;
diff --git a/src/mapgen_fractal.cpp b/src/mapgen_fractal.cpp
index 0430f92ff..810645abb 100644
--- a/src/mapgen_fractal.cpp
+++ b/src/mapgen_fractal.cpp
@@ -56,7 +56,8 @@ MapgenFractal::MapgenFractal(int mapgenid, MapgenParams *params, EmergeManager *
 	//// amount of elements to skip for the next index
 	//// for noise/height/biome maps (not vmanip)
 	this->ystride = csize.X;
-	this->zstride = csize.X * (csize.Y + 2);
+	// 1-down overgeneration
+	this->zstride_1d = csize.X * (csize.Y + 1);
 
 	this->biomemap  = new u8[csize.X * csize.Z];
 	this->heightmap = new s16[csize.X * csize.Z];
@@ -85,8 +86,9 @@ MapgenFractal::MapgenFractal(int mapgenid, MapgenParams *params, EmergeManager *
 	noise_filler_depth = new Noise(&sp->np_filler_depth, seed, csize.X, csize.Z);
 
 	//// 3D terrain noise
-	noise_cave1 = new Noise(&sp->np_cave1, seed, csize.X, csize.Y + 2, csize.Z);
-	noise_cave2 = new Noise(&sp->np_cave2, seed, csize.X, csize.Y + 2, csize.Z);
+	// 1-down overgeneraion
+	noise_cave1 = new Noise(&sp->np_cave1, seed, csize.X, csize.Y + 1, csize.Z);
+	noise_cave2 = new Noise(&sp->np_cave2, seed, csize.X, csize.Y + 1, csize.Z);
 
 	//// Biome noise
 	noise_heat           = new Noise(&params->np_biome_heat,           seed, csize.X, csize.Z);
@@ -694,19 +696,19 @@ void MapgenFractal::generateCaves(s16 max_stone_y)
 	for (s16 x = node_min.X; x <= node_max.X; x++, index2d++) {
 		bool column_is_open = false;  // Is column open to overground
 		bool is_tunnel = false;  // Is tunnel or tunnel floor
-		u32 vi = vm->m_area.index(x, node_max.Y + 1, z);
-		u32 index3d = (z - node_min.Z) * zstride + (csize.Y + 1) * ystride +
+		u32 vi = vm->m_area.index(x, node_max.Y, z);
+		u32 index3d = (z - node_min.Z) * zstride_1d + csize.Y * ystride +
 			(x - node_min.X);
 		// Biome of column
 		Biome *biome = (Biome *)bmgr->getRaw(biomemap[index2d]);
 
-		for (s16 y = node_max.Y + 1; y >= node_min.Y - 1;
-				y--, index3d -= ystride, vm->m_area.add_y(em, vi, -1)) {
-			// Don't excavate the overgenerated stone at node_max.Y + 1,
-			// this creates a 'roof' over the tunnel, preventing light in
-			// tunnels at mapchunk borders when generating mapchunks upwards.
-			if (y > node_max.Y)
-				continue;
+		// Don't excavate the overgenerated stone at node_max.Y + 1,
+		// this creates a 'roof' over the tunnel, preventing light in
+		// tunnels at mapchunk borders when generating mapchunks upwards.
+		// This 'roof' is removed when the mapchunk above is generated.
+		for (s16 y = node_max.Y; y >= node_min.Y - 1; y--,
+				index3d -= ystride,
+				vm->m_area.add_y(em, vi, -1)) {
 
 			content_t c = vm->m_data[vi].getContent();
 			if (c == CONTENT_AIR || c == biome->c_water_top ||
diff --git a/src/mapgen_fractal.h b/src/mapgen_fractal.h
index ffb2acfb9..8c21a8a4e 100644
--- a/src/mapgen_fractal.h
+++ b/src/mapgen_fractal.h
@@ -65,7 +65,7 @@ public:
 	BiomeManager *bmgr;
 
 	int ystride;
-	int zstride;
+	int zstride_1d;
 	u16 formula;
 	bool julia;
 
diff --git a/src/mapgen_v7.cpp b/src/mapgen_v7.cpp
index 42fbe4423..54abba145 100644
--- a/src/mapgen_v7.cpp
+++ b/src/mapgen_v7.cpp
@@ -59,7 +59,8 @@ MapgenV7::MapgenV7(int mapgenid, MapgenParams *params, EmergeManager *emerge)
 	//// amount of elements to skip for the next index
 	//// for noise/height/biome maps (not vmanip)
 	this->ystride = csize.X;
-	this->zstride = csize.X * (csize.Y + 2);
+	// 1-down overgeneration
+	this->zstride_1d = csize.X * (csize.Y + 1);
 
 	this->biomemap        = new u8[csize.X * csize.Z];
 	this->heightmap       = new s16[csize.X * csize.Z];
@@ -80,10 +81,12 @@ MapgenV7::MapgenV7(int mapgenid, MapgenParams *params, EmergeManager *emerge)
 	noise_ridge_uwater    = new Noise(&sp->np_ridge_uwater,    seed, csize.X, csize.Z);
 
 	//// 3d terrain noise
+	// 1-up 1-down overgeneration
 	noise_mountain = new Noise(&sp->np_mountain, seed, csize.X, csize.Y + 2, csize.Z);
 	noise_ridge    = new Noise(&sp->np_ridge,    seed, csize.X, csize.Y + 2, csize.Z);
-	noise_cave1    = new Noise(&sp->np_cave1,    seed, csize.X, csize.Y + 2, csize.Z);
-	noise_cave2    = new Noise(&sp->np_cave2,    seed, csize.X, csize.Y + 2, csize.Z);
+	// 1-down overgeneraion
+	noise_cave1    = new Noise(&sp->np_cave1,    seed, csize.X, csize.Y + 1, csize.Z);
+	noise_cave2    = new Noise(&sp->np_cave2,    seed, csize.X, csize.Y + 1, csize.Z);
 
 	//// Biome noise
 	noise_heat           = new Noise(&params->np_biome_heat,           seed, csize.X, csize.Z);
@@ -199,7 +202,7 @@ void MapgenV7Params::writeParams(Settings *settings) const
 }
 
 
-///////////////////////////////////////
+///////////////////////////////////////////////////////////////////////////////
 
 
 int MapgenV7::getSpawnLevelAtPoint(v2s16 p)
@@ -451,41 +454,6 @@ bool MapgenV7::getMountainTerrainFromMap(int idx_xyz, int idx_xz, s16 y)
 }
 
 
-#if 0
-void MapgenV7::carveRivers() {
-	MapNode n_air(CONTENT_AIR), n_water_source(c_water_source);
-	MapNode n_stone(c_stone);
-	u32 index = 0;
-
-	int river_depth = 4;
-
-	for (s16 z = node_min.Z; z <= node_max.Z; z++)
-	for (s16 x = node_min.X; x <= node_max.X; x++, index++) {
-		float terrain_mod  = noise_terrain_mod->result[index];
-		NoiseParams *np = noise_terrain_river->np;
-		np.persist = noise_terrain_persist->result[index];
-		float terrain_river = NoisePerlin2DNoTxfm(np, x, z, seed);
-		float height = terrain_river * (1 - abs(terrain_mod)) *
-						noise_terrain_river->np.scale;
-		height = log(height * height); //log(h^3) is pretty interesting for terrain
-
-		s16 y = heightmap[index];
-		if (height < 1.0 && y > river_depth &&
-			y - river_depth >= node_min.Y && y <= node_max.Y) {
-
-			for (s16 ry = y; ry != y - river_depth; ry--) {
-				u32 vi = vm->m_area.index(x, ry, z);
-				vm->m_data[vi] = n_air;
-			}
-
-			u32 vi = vm->m_area.index(x, y - river_depth, z);
-			vm->m_data[vi] = n_water_source;
-		}
-	}
-}
-#endif
-
-
 int MapgenV7::generateTerrain()
 {
 	s16 stone_surface_min_y;
@@ -765,6 +733,112 @@ void MapgenV7::dustTopNodes()
 }
 
 
+void MapgenV7::generateCaves(s16 max_stone_y)
+{
+	if (max_stone_y < node_min.Y)
+		return;
+
+	noise_cave1->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
+	noise_cave2->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
+
+	v3s16 em = vm->m_area.getExtent();
+	u32 index2d = 0;
+
+	for (s16 z = node_min.Z; z <= node_max.Z; z++)
+	for (s16 x = node_min.X; x <= node_max.X; x++, index2d++) {
+		bool column_is_open = false;  // Is column open to overground
+		bool is_tunnel = false;  // Is tunnel or tunnel floor
+		// Indexes at column top (node_max.Y)
+		u32 vi = vm->m_area.index(x, node_max.Y, z);
+		u32 index3d = (z - node_min.Z) * zstride_1d + csize.Y * ystride +
+			(x - node_min.X);
+		// Biome of column
+		Biome *biome = (Biome *)bmgr->getRaw(biomemap[index2d]);
+
+		// Don't excavate the overgenerated stone at node_max.Y + 1,
+		// this creates a 'roof' over the tunnel, preventing light in
+		// tunnels at mapchunk borders when generating mapchunks upwards.
+		// This 'roof' is removed when the mapchunk above is generated.
+		for (s16 y = node_max.Y; y >= node_min.Y - 1; y--,
+				index3d -= ystride,
+				vm->m_area.add_y(em, vi, -1)) {
+
+			content_t c = vm->m_data[vi].getContent();
+			if (c == CONTENT_AIR || c == biome->c_water_top ||
+					c == biome->c_water) {
+				column_is_open = true;
+				continue;
+			}
+			// Ground
+			float d1 = contour(noise_cave1->result[index3d]);
+			float d2 = contour(noise_cave2->result[index3d]);
+			if (d1 * d2 > 0.3f && ndef->get(c).is_ground_content) {
+				// In tunnel and ground content, excavate
+				vm->m_data[vi] = MapNode(CONTENT_AIR);
+				is_tunnel = true;
+			} else if (is_tunnel && column_is_open &&
+					(c == biome->c_filler || c == biome->c_stone)) {
+				// Tunnel entrance floor
+				vm->m_data[vi] = MapNode(biome->c_top);
+				column_is_open = false;
+				is_tunnel = false;
+			} else {
+				column_is_open = false;
+				is_tunnel = false;
+			}
+		}
+	}
+
+	if (node_min.Y >= water_level)
+		return;
+
+	PseudoRandom ps(blockseed + 21343);
+	u32 bruises_count = ps.range(0, 2);
+	for (u32 i = 0; i < bruises_count; i++) {
+		CaveV7 cave(this, &ps);
+		cave.makeCave(node_min, node_max, max_stone_y);
+	}
+}
+
+
+///////////////////////////////////////////////////////////////
+
+
+#if 0
+void MapgenV7::carveRivers() {
+	MapNode n_air(CONTENT_AIR), n_water_source(c_water_source);
+	MapNode n_stone(c_stone);
+	u32 index = 0;
+
+	int river_depth = 4;
+
+	for (s16 z = node_min.Z; z <= node_max.Z; z++)
+	for (s16 x = node_min.X; x <= node_max.X; x++, index++) {
+		float terrain_mod  = noise_terrain_mod->result[index];
+		NoiseParams *np = noise_terrain_river->np;
+		np.persist = noise_terrain_persist->result[index];
+		float terrain_river = NoisePerlin2DNoTxfm(np, x, z, seed);
+		float height = terrain_river * (1 - abs(terrain_mod)) *
+						noise_terrain_river->np.scale;
+		height = log(height * height); //log(h^3) is pretty interesting for terrain
+
+		s16 y = heightmap[index];
+		if (height < 1.0 && y > river_depth &&
+			y - river_depth >= node_min.Y && y <= node_max.Y) {
+
+			for (s16 ry = y; ry != y - river_depth; ry--) {
+				u32 vi = vm->m_area.index(x, ry, z);
+				vm->m_data[vi] = n_air;
+			}
+
+			u32 vi = vm->m_area.index(x, y - river_depth, z);
+			vm->m_data[vi] = n_water_source;
+		}
+	}
+}
+#endif
+
+
 #if 0
 void MapgenV7::addTopNodes()
 {
@@ -859,70 +933,3 @@ void MapgenV7::addTopNodes()
 	}
 }
 #endif
-
-
-void MapgenV7::generateCaves(s16 max_stone_y)
-{
-	if (max_stone_y < node_min.Y)
-		return;
-
-	noise_cave1->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
-	noise_cave2->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
-
-	v3s16 em = vm->m_area.getExtent();
-	u32 index2d = 0;
-
-	for (s16 z = node_min.Z; z <= node_max.Z; z++)
-	for (s16 x = node_min.X; x <= node_max.X; x++, index2d++) {
-		bool column_is_open = false;  // Is column open to overground
-		bool is_tunnel = false;  // Is tunnel or tunnel floor
-		u32 vi = vm->m_area.index(x, node_max.Y + 1, z);
-		u32 index3d = (z - node_min.Z) * zstride + (csize.Y + 1) * ystride +
-			(x - node_min.X);
-		// Biome of column
-		Biome *biome = (Biome *)bmgr->getRaw(biomemap[index2d]);
-
-		for (s16 y = node_max.Y + 1; y >= node_min.Y - 1;
-				y--, index3d -= ystride, vm->m_area.add_y(em, vi, -1)) {
-			// Don't excavate the overgenerated stone at node_max.Y + 1,
-			// this creates a 'roof' over the tunnel, preventing light in
-			// tunnels at mapchunk borders when generating mapchunks upwards.
-			if (y > node_max.Y)
-				continue;
-
-			content_t c = vm->m_data[vi].getContent();
-			if (c == CONTENT_AIR || c == biome->c_water_top ||
-					c == biome->c_water) {
-				column_is_open = true;
-				continue;
-			}
-			// Ground
-			float d1 = contour(noise_cave1->result[index3d]);
-			float d2 = contour(noise_cave2->result[index3d]);
-			if (d1 * d2 > 0.3f && ndef->get(c).is_ground_content) {
-				// In tunnel and ground content, excavate
-				vm->m_data[vi] = MapNode(CONTENT_AIR);
-				is_tunnel = true;
-			} else if (is_tunnel && column_is_open &&
-					(c == biome->c_filler || c == biome->c_stone)) {
-				// Tunnel entrance floor
-				vm->m_data[vi] = MapNode(biome->c_top);
-				column_is_open = false;
-				is_tunnel = false;
-			} else {
-				column_is_open = false;
-				is_tunnel = false;
-			}
-		}
-	}
-
-	if (node_min.Y >= water_level)
-		return;
-
-	PseudoRandom ps(blockseed + 21343);
-	u32 bruises_count = ps.range(0, 2);
-	for (u32 i = 0; i < bruises_count; i++) {
-		CaveV7 cave(this, &ps);
-		cave.makeCave(node_min, node_max, max_stone_y);
-	}
-}
diff --git a/src/mapgen_v7.h b/src/mapgen_v7.h
index 82f89387b..9fdecf592 100644
--- a/src/mapgen_v7.h
+++ b/src/mapgen_v7.h
@@ -59,7 +59,7 @@ public:
 	BiomeManager *bmgr;
 
 	int ystride;
-	int zstride;
+	int zstride_1d;
 	u32 spflags;
 
 	v3s16 node_min;
diff --git a/src/mapgen_valleys.cpp b/src/mapgen_valleys.cpp
index 34a316abd..be122aace 100644
--- a/src/mapgen_valleys.cpp
+++ b/src/mapgen_valleys.cpp
@@ -74,6 +74,8 @@ MapgenValleys::MapgenValleys(int mapgenid, MapgenParams *params, EmergeManager *
 	//// for noise/height/biome maps (not vmanip)
 	this->ystride = csize.X;
 	this->zstride = csize.X * (csize.Y + 2);
+	// 1-down overgeneration
+	this->zstride_1d = csize.X * (csize.Y + 1);
 
 	this->biomemap  = new u8[csize.X * csize.Z];
 	this->heightmap = new s16[csize.X * csize.Z];
@@ -113,10 +115,12 @@ MapgenValleys::MapgenValleys(int mapgenid, MapgenParams *params, EmergeManager *
 	noise_valley_profile     = new Noise(&sp->np_valley_profile,     seed, csize.X, csize.Z);
 
 	//// 3D Terrain noise
-	noise_cave1             = new Noise(&sp->np_cave1,             seed, csize.X, csize.Y + 2, csize.Z);
-	noise_cave2             = new Noise(&sp->np_cave2,             seed, csize.X, csize.Y + 2, csize.Z);
+	// 1-up 1-down overgeneration
 	noise_inter_valley_fill = new Noise(&sp->np_inter_valley_fill, seed, csize.X, csize.Y + 2, csize.Z);
-	noise_massive_caves     = new Noise(&sp->np_massive_caves,     seed, csize.X, csize.Y + 2, csize.Z);
+	// 1-down overgeneraion
+	noise_cave1             = new Noise(&sp->np_cave1,             seed, csize.X, csize.Y + 1, csize.Z);
+	noise_cave2             = new Noise(&sp->np_cave2,             seed, csize.X, csize.Y + 1, csize.Z);
+	noise_massive_caves     = new Noise(&sp->np_massive_caves,     seed, csize.X, csize.Y + 1, csize.Z);
 
 	//// Biome noise
 	noise_heat_blend     = new Noise(&params->np_biome_heat_blend,     seed, csize.X, csize.Z);
@@ -885,7 +889,7 @@ void MapgenValleys::generateCaves(s16 max_stone_y)
 	if (node_max.Y <= massive_cave_depth) {
 		noise_massive_caves->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
 
-		for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
+		for (s16 y = node_min.Y - 1; y <= node_max.Y; y++) {
 			float tcave = massive_cave_threshold;
 
 			if (y < yblmin) {
@@ -923,19 +927,17 @@ void MapgenValleys::generateCaves(s16 max_stone_y)
 		Biome *biome = (Biome *)bmgr->getRaw(biomemap[index_2d]);
 		bool air_above = false;
 		bool underground = false;
-		u32 index_data = vm->m_area.index(x, node_max.Y + 1, z);
-
-		index_3d = (z - node_min.Z) * zstride + (csize.Y + 1) * ystride + (x - node_min.X);
+		u32 index_data = vm->m_area.index(x, node_max.Y, z);
+		index_3d = (z - node_min.Z) * zstride_1d + csize.Y * ystride + (x - node_min.X);
 
 		// Dig caves on down loop to check for air above.
-		for (s16 y = node_max.Y + 1;
-				y >= node_min.Y - 1;
-				y--, index_3d -= ystride, vm->m_area.add_y(em, index_data, -1)) {
-			// Don't excavate the overgenerated stone at node_max.Y + 1,
-			// this creates a 'roof' over the tunnel, preventing light in
-			// tunnels at mapchunk borders when generating mapchunks upwards.
-			if (y > node_max.Y)
-				continue;
+		// Don't excavate the overgenerated stone at node_max.Y + 1,
+		// this creates a 'roof' over the tunnel, preventing light in
+		// tunnels at mapchunk borders when generating mapchunks upwards.
+		// This 'roof' is removed when the mapchunk above is generated.
+		for (s16 y = node_max.Y; y >= node_min.Y - 1; y--,
+				index_3d -= ystride,
+				vm->m_area.add_y(em, index_data, -1)) {
 
 			float terrain = noise_terrain_height->result[index_2d];
 
diff --git a/src/mapgen_valleys.h b/src/mapgen_valleys.h
index 6b3eb9cfe..4ad2d2076 100644
--- a/src/mapgen_valleys.h
+++ b/src/mapgen_valleys.h
@@ -106,6 +106,7 @@ private:
 
 	int ystride;
 	int zstride;
+	int zstride_1d;
 
 	float map_gen_limit;