graphics as the entire level

[Hiro]

i was wondering if anyone has considering making an overworld where all the levels are a collection of graphics. i mean that the level functionality is covered by an image which the player walks over. instead of using a tile set, the overworld just uses images

i know gate made a castle on npulse this way, and it turned out looking really well, especially since he could add small details to unique places, which with tilesets would make them all look the same. it also tends to make making levels easier, since tile errors don't matter anymore - the image will cover them up. so long as the tiles are in the right place to block the player and what-not, the image takes care of the rest

has it ever been done?