demo instructions in the cart itself, code and even spritesheet reasonably commented.
all tiles connect with each other by default, but that's changeable in the update_tile method.

feel free to make modifications, additions, optimisations, etc

made for a quite large and special sorta-secret project ;)

tool tools autotile tilemap

That's really cool! I'm always baffled by how many sprites are needed for auto tiling.

I often remember the Rpg Maker 2000 and how it included those features as if it was nothing. There also was an interesting simplicity to the way its autotiles worked - they needed less sprites and still worked perfectly. I wish modern tiling editors would work similarly, reducing the amount of tiles that need to be provided as graphics.

@Odrez: dunno if you've gotten more info by now, but there is a pico-8 tutorial for more efficient tilesets:

the issue is that
1) i wanted to have multiple variations for each tile, and
2) wanted to only calculate the tiles once in the beginning, and for small segments when tiles were added/removed.

the above method would either require some separate way of storing the tiles or be more restricted
although, if you check the gfx file, you'll notice that i did make a more efficient tileset (though with less variation), but just never got to implementing the change :/

if i get back into working on things in picotron, i'd like to clean up this tool as well, largely even for my own sake lol