paste in uncompressed art data as hexadecimal (no 0x or newlines) into the first box, then a palette as hexadecimal. if the tile doesn't render, it's a blank tile. press r and try again with a different number. sonic 2's sonic tiles and palette are loaded by default.
(you're free to do whatever you want with this) it renders uncompressed 8x8 tiles of most Megadrive/Genesis sonic games. ...i think. i haven't tested with anything but S2's sonic tiles.