This topic reminded of something I started on years ago, but never actually developed into a game. I post it here if anyone wants to finish it or just as a reference. Assembles with asm6.
Code:
D-Pad: move cursor around
B+up: cycle to next tile
B+down: cycle to previous tile
A: place tile
Select: clear tile
B+up: cycle to next tile
B+down: cycle to previous tile
A: place tile
Select: clear tile