GREAT GAME
The only disappointment is that there are no enemies that are SUPER hard to kill. I mean, once you mutate your rat to 500, and put only level 2 cybernetics (super muscles [light red], attack chip, atomic reactor chest) there are no enemies that can stand up to you if you have fused your rat with two or more guys already. Anyways, there are a couple of improvements I would suggest:
1. Once you have beaten the last guy in the arena, allow the purchasing of master miners, researchers, and engineers (50 in each stat accordingly maybe?) so its possible to make those higher level cybernetics pieces (levels 3, 4, and 5) without having to make 1000 of the level 2 ones.
2. Once you have beaten the last guy in the arena, allow access to a second arena tier with only three guys that are super hard to beat. That means that the last guy should only be beatable with level 500, fused twice, level 5 cybernetics rats. This would give a nice finishing feeling to the game, instead of what I got, which was ending with level 500 and level 2 cybernetics...
GLITCH: I only found one glitch in this game. It was that when you had 15 of an item, and tried to create an item that required 2 of that item to make, you would use up all the resources, but only get 7 of the item. The fix would be to make it so that you get 7, but end up with 1 of the original resource remaining.
Other than all of that, FANTASTIC game! :) Kept me entertained for at least 7 hours.