I think you could use some polish on the user interface. Keyboard-navigatable menus would make the whole experience a lot better, rather than having to go back and forth between keyboard and mouse.

An alternate control scheme I was thinking of: Up (instead of down) to do a controlled drop, Down (instead of space) for an auto-drop, left/right (instead of up) to cycle through the colors. This will give it good one-handed play and utilize the left/right buttons, many make it quicker to chose a specific color.

Gameplay was definitely unique. Not sure it's my cup of tea. Even though the timing is somewhat forgiving (good job on the snapping for that btw) it still felt a bit tedious to wait for a precise moment to place a specific block after several misses.

Ah nice! Can you make it mobile friendly?