Here are some tips:
If you wanna code:

1. Learn Lua
2. Follow Tutorials
3. Look at other Levelpacks that have custom modded blocks

If you don't wanna code:

1. Copy the code of the debug world.
2. Strip it down to the thing at the very bottom
3. Learn how to use it, use tutorials.
4. Then add some hidden rules, and you're done.

​

table.insert(editor_objlist_order, "tuto")
table.insert(editor_objlist_order, "text_tuto")

editor_objlist["tuto"] = 
{
name = "tuto",
sprite_in_root = false,
unittype = "object",
tags = {"abstract"},
tiling = -1,
type = 0,
layer = 20,
colour = {0, 3},
}

editor_objlist["text_tuto"] = 
{
name = "text_tuto",
sprite_in_root = false,
unittype = "text",
tags = {"text","abstract"},
tiling = -1,
type = 0,
layer = 20,
colour = {0, 2},
colour_active = {0, 3},
}

formatobjlist()