Well-made game
This game is great: there are a variety of interesting perks (upgrades) to choose from, many weapons, and a good pace with introducing different enemies and challenges. Congratulations to MoonMana for a smart and well-made game!
When playing, beware how you spend your perks! In the earlier levels, Radioactive Bullets and Repair Drone are very helpful. To defeat the Prison Keeper, I suggest getting both levels of Boost Attack Speed and The Chosen One, and keep a spare point or two for Instant Repairs.