This is Picocross, a picross video game made for PICO-8. Picross has always been one of my favorite puzzle games, so I made this to share with people. Have fun!
The rules are explained lightly in the ingame menu, "How to play", but if you're still having trouble, wikipedia has a nice article on how to play the game as well.
As a note, if you finish all the levels and get that bonus content, in order to actually do anything with it, you're going to need to download the cart and own PICO-8 yourself. There is an alternate way to unlock that bonus content, one of the puzzles gives a hint.

Well, I'm setz. I go by a few names. My twitter is @splixel. If you have a question or comment, that's the best place for it.
I do pixel art, gamedev, speedruns, play fighting games, I used to stream on twitch when I had internet. I work at a junkyard, yell at kids to get off my lawn. Normal human things.
I hope you enjoy both this and WaGa!