I played your game a bit. Here are few notes:
- The font is very hard to read (letters like H-K, U-V a practically indistinguishable, X looks like a solid block for some reason). Since you already have UI options like palette, I suggest adding “normal” font option (or maybe some more readable pixel font).
- “Enter” for rotation is very strange, I repeatedly mixed up controls when playing. Something like “S” to rotate, “Space” to drop would be more natural for me. Maybe just add changeable control settings.
- Holding down “drop” key continues dropping next piece after landing the first one, which is frustrating.
- Conversely, auto-repeat on left/right movement would be welcome
- The fact that diagonal matches also work is not obvious at first, maybe worth mentioning in the description
- Maybe add point bonus for dropping pieces
- Fully same-color pieces feel “too good”, maybe remove them
- Please add lines indicating field limits it is awkward to play without them
- I maybe noticed that sometimes when a piece completes multiple lines at once, some lines are not destroyed. Not sure though, as it is hard to test/reproduce.
- When the game progresses to “new stage”, I suggest adding some message / indication.
- I am quite sure that I played very old game with this exact gameplay, but can not remember the name. Did you also play it?