Unless there's a different kind of rotation in later levels, what happens after forming a line is equivalent to having the existing structure "collapse" under gravity (any suspended blocks fall straight down). This is purely beneficial to the player, and means there's a bit less strategy involved than I would first have thought: you can just play normally and any errors will get fixed every time you complete a line!
Edit: I'm kind of wrong about that because there's a different kind of rotation that happens if you form a complete vertical line.
Is it even possible to "complete a vertical line"? In normal Tetris, completing a vertical line means you've lost, because the screen has filled up.
Various suggestions: Make completing a line rotate the board instead of flipping it. Make completing a 4x4 quadrant rotate the board in the appropriate direction. Make rotating the board not re-fall the blocks (since as others have said, this makes the game trivial): this would make it almost instant death to rotate the board twice in the same direction in a row, which might not be a bad idea.
Pretty cool, but the sudden ramp up in speed makes it impossible around 7000 points - speed should probably increase more linearly
This feels like a bug, when the board flips, the pieces lose consistency. I get that you can cut pieces, but no sure why I'm getting spaces in between a single piece as it falls, whether it was cut or not.
This is good, I definitely had fun! Really cool original idea! I liked how I discovered the "vertical line" win by accident when I thought I was going to lose. (I didn't quite get the instructions at first, but it made sense when playing.)
A couple of issues I noticed:
- some pieces rotate in an odd way, as if around an off-centre fixed point. It felt unlike regular Tetris and caused losses that otherwise wouldn't have been in tight spots. Like the piece would "jump" over an entire grid section unexpectedly. It's especially noticable with the long piece.
- on my system, trying a "hard mode" game after a few normal mode games, the hard mode immediately began insanely fast. Repeat plays then caused it to keep speeding up even further each restart, eventually going into endless loop by itself, where it seemed to be so fast it couldn't correctly check gamestate. In these restarts, no pieces would appear, but the score kept increasing anyway, eventually up to some very high number (eg, >70,000) before it'd finally decide a game over state. Each successive game would do the same thing, but advance to yet higher scores.
EDIT: Reproduced the second issue, and noticed hundreds of "Skipping tick during rotation" messages in the console. The procedure for me to reproduce was: play a normal game until you hit the 6000-7000 huge speed-up and game over, then keep playing hard mode games repeatedly, until it takes over.