The opening cinema needs to allow clicking to close each balloon. It goes by entirely too slowly, so I just skip it. Then the game doesn't really make sense. (You shouldn't rely on cutscenes for story anyway. Make the story revealed as a first level of the game.)
Look up the word interpolation and then do a drawing game that doesn't look ugly. And the controls when falling down a tiny step are annoying since you can't jump. And being able to draw under yourself makes the levels feel boring. And the laser being able to shoot you at spawn is lame.
This isn't in the same league as the sequel. If I hadn't seen the other one I'd never have even bothered with it. I kept waiting for the story to start.
Bug in x23. Shoot left at the purple bouncers, run to the right, push the box against the disappearing square to the right, hold on to right, and you instantly die when the floor disappears.
Have the mouse losing focus count as a mouse up. It is nearly impossible to kill guys on the very left edge of a board since the mouse goes outside the window.