nalc_game/mods/creative/init.lua

creative = {}

local creative_mode_cache = minetest.setting_getbool("creative_mode")

function creative.is_enabled_for(name)
	return creative_mode_cache
end

dofile(minetest.get_modpath("creative") .. "/inventory.lua")

if creative_mode_cache then
	-- Dig time is modified according to difference (leveldiff) between tool
	-- 'maxlevel' and node 'level'. Digtime is divided by the larger of
	-- leveldiff and 1.
	-- To speed up digging in creative, hand 'maxlevel' and 'digtime' have been
	-- increased such that nodes of differing levels have an insignificant
	-- effect on digtime.
	local digtime = 42
	local caps = {times = {digtime, digtime, digtime}, uses = 0, maxlevel = 256}

	minetest.register_item(":", {
		type = "none",
		wield_image = "wieldhand.png",
		wield_scale = {x = 1, y = 1, z = 2.5},
		range = 10,
		tool_capabilities = {
			full_punch_interval = 0.5,
			max_drop_level = 3,
			groupcaps = {
				crumbly = caps,
				cracky  = caps,
				snappy  = caps,
				choppy  = caps,
				oddly_breakable_by_hand = caps,
			},
			damage_groups = {fleshy = 10},
		}
	})
end

-- Unlimited node placement
minetest.register_on_placenode(function(pos, newnode, placer, oldnode, itemstack)
	return creative.is_enabled_for(placer:get_player_name())
end)

-- Don't pick up if the item is already in the inventory
local old_handle_node_drops = minetest.handle_node_drops
function minetest.handle_node_drops(pos, drops, digger)
	if not digger or not digger:is_player() then
		return
	end
	if not creative.is_enabled_for(digger:get_player_name()) then
		return old_handle_node_drops(pos, drops, digger)
	end
	local inv = digger:get_inventory()
	if inv then
		for _, item in ipairs(drops) do
			if not inv:contains_item("main", item, true) then
				inv:add_item("main", item)
			end
		end
	end
end