I see a lot of potential in this one, but as the title suggests, it is a good prototype.
I like the variety, choosing one of three different mechs is nice. I picked the medium one. The enemies are really simple but fun to shoot at.
My biggest dislike about this game is, that there is no real goal here. I played for like 30 minutes, and nothing really happens. The enemies do not pose a thread at all, since the power station has an almost infinite health. The mech as well has a good way of defending itself with the shield thing.
The controls, albeit weird choosing arrow-keys instead of WASD, are really good! It made a lot of fun shooting the enemies.