Played until I beat level 6, and then couldn't figure out how to open levels 7+. The entire time the screen was bigger than my 1080p monitor and I couldn't change it (on windows 7).
Dialog box rapid fire:
Remove the entire pre-title intro text. If you really want that character interaction, spread it out over the game
Speed up the title fade in
Show [T] somewhere so people know how to foward dialog. Might as well make spacebar, enter, right arrow, down arrow, and F also work as advance dialog since they don't do anything else while looking at dialog
Make pressing dailog-advance while the text is slowly appearing skip the text-slowly-appears animation
Make the key to open "!" boxes F or X or whatever the use key is, in addition to T
Make the backgrounds visible for the first areas. You almost lost me since the game looked so visually boring
Don't turn on walljumping, hovering, etc half way through a level. When I went to the teleporter, I was relying on the game introducing some way to save me so it was possible to run the level again
When the character dies, reset touched-blocks. If while falling into the void you touch any extra blocks, the optimal strategy is to always reset on the computer, since this isnt done automatically
Make reseting the level on the computer take less button presses.
On the 2nd run through a level, faintly show the removed blocks. This is so if you made the level impossible on your first run, you will know how to fix it.
It seems like there is no acceleration for moving. Just instant velocity for pressing a key. This makes it very difficult to hit 1 wide platforms
Blue-monster introduction seemed skipped. Maybe have their intro be a simpler level
There are some levels with small puzzle elements, but it seems like 90% is just basic platform-to-platform stuff.