Can't go wrong with a classic. Great job!

It isn't anything new but it really does fit the theme well! Your implementation looks really cool too.

I would have loved if you added some nice background music. I'd also recommend you to put the default controls somewhere on the LD page here, I didn't know how to rotate my pieces and had to reset at first. I found them in the main menu and they even seem to be customizable which is amazing, but it will definitely be helpful for lazy people like me when they can read them right away :). Also, the game uses fully random pieces instead of some "bag" system right? I had a really long long piece drought so I think so (or I am just really bad :D ). If yes that isn't bad at all too, I think original NES tetris does it the same and it is perfectly valid :).

Had a good time playing overall :).

@nima thanks for the feedback, that's what I thought :-D

@tygrak thanks for the detailed review, you are right, I actually wanted to show the controls on the left side in-game, where there is black empty space right now. I did not do it in time but as you specifically mention it, I might add it now anyway. As far as I see it, this is not against Compo rules. It improves usability and does not change the game.

Actually, the blocks are almost all random. Only the first and possibly the second block in a game are restricted.
I hate it when I start with a Z or S piece because it always leaves an empty spot under it, no matter how you rotate it. That is why I specifically disallow Z and S for the first piece. Also for the second piece, if the first one was an O.
I documented this in the code:

https://github.com/gonutz/ld50/blob/694fc52db0c816f0ca2f54435ba2bf5bcdcbe803/blocks.go#L18

All other pieces are indeed random, so a long piece drought can happen :-)

Music and sounds were off the table due to time limits, unfortunately.

Thanks for playing the game, I will be checking out your games in return tonight :-)

You have not used one of the big engines, that's cool. I am impressed by the low line count. A keybindings menu is always appreciated.

I would have liked sounds, line clear animations and some wall kicks.
Being able to move the tetromino when it touches the ground before it locks is nice too. You have made it in a way that it needs to "fall" an extra line to be locked, some Tetrises have a distinct delay for that as well as non-locking drops.