There are no instruction on what keys to use or how to play. It took a while to understand that with the tank minigame you had to hold space down to launch the poor guy further. It wasn't that you drive the tank around.
The asteroid game is good (though the onscreen buttons cover a bit of the play area). It's a twist on the usual space shooter games - the asteroids need destroying, and the space craft can't be destroyed and need to be avoided.
The platformer is just too hard for me. I couldn't get past the Rhino. The player collision box is too large, and it's a bit of guesswork as to when to jump. However, I like the idea that you entice the player with an exit that's unreachable, because the need to figure out the alternative route.
If you fix up the platformer collision boxes it would make for a good set of minigames.