Quite bad
The graphics were ok but could've been better.
The music was just an anoying and very short loop.
The controls were truly horrible, why not make zim turn following the mouse???
When you get in the upper part of the screen in the first level, Zim gets jammed in the wall and you can't get out.
And finally, some canons were between four walls, couldn't shoot you or get shoot, what's up with that???
So yeah, as an Invader Zim fan, I think this game is really bad. Try harder next time.