Here's a guide in spoilers for unlocking the three characters in case anyone really needs the help.

Sticky in a bedroom: Using a character with Bitflip as a pocket item spam Bitflip inside of a bedroom until you get a sticky keys popup. This does not work on the Home floor.

Pirate: Even if you haven't unlocked a character you can still walk out of the room with them. You need to do that, and survive to the next floor, wherein a trophy will spawn in the first room. Pick the trophy up and the character is yours! Your character has standard stats and the Bitflip pocket item, but using it is not helpful, as the corrupted items are forbidden and will only give negative effects. In addition, all the items that spawn seem to be of very low quality and the game itself does not take kindly to pirates, trying to stop you at every point. Have fun trying to survive!

Unzip a shop: You need to use the ZIP BOMBER character, go into a shop and use your pocket item until everything the shop is selling explodes. The shopkeeper will not be happy though, dropping a note informing you that you broke the law. Pick it up, and then try to survive getting to the next floor, wherein a trophy will spawn in the first room. Pick the trophy up and you've unlocked the character!


Hopefully this guide can be of use to someone!