This is actually not that good of a game.
Not 10 dollars worth and I'll tell you why:
There is no variability. The whole point of a game is to add some dynamic player experience and this game offers none. I don't mind that you only have like 20 different guns, but at least put some randomness in that. Let's say a gun does 20 damage. That should be changed to 15-25 damage, and even that should have some variability. That itself should vary from a base of 13-17 and a max of 20-30, completely random. You could pick up the same gun twice off what the enemy drops and one could do 13-20 but another could do 16-28, you just don't know, and that's the big thing this game is missing.
The same applies with levels. That's cool that there is 490 rooms, but at least have your maps randomly generated some how. Not the rooms per say, but the map should alter every time you play.
Armor, why can't you update this robot?
Stats? I saw a leveling up system but no stats. There is so many good stats you can benefit off of like speed, armor, damage, etc.
I think the shield principle is kind of lame because you don't have any armor.
What is with the background noise?
I don't think you've ever shot steel before, but bullets ricochet.