Two Suggestion: 1. Make an "Relay" upgrade that make certain components works only in a given (selected by the user) temperature range. 2. Since Heat exchangers doesnt transmit heat to reactor anymore its hard to keep temperature equilibrated at a given range, give to the players more control over this!
The game is too much polluted for a Bullet Hell... Big Enemies, Enemies Debris, Coins, Hearts, Mana/Fuel, Books, Dude's Items, Two big characters in the screen and a Polluted colorful background makes the things very hard to dodge enemy bullets. Also, the small hitbox of the items and the absence of a magnet upgrade make a very frustrating situation to catch these items.
 "Learn to Fly 3"){kind=icon}
 "Reactor Incremental"){kind=icon}
 "Save the Earth! - The Incremental -"){kind=icon}
 "Auto Turret"){kind=icon}
 "Soccer Physics"){kind=icon}
 "Nether Runner"){kind=icon}
 "Dream Car Racing"){kind=icon}
 "L.I.F.E."){kind=icon}
 "Defendless"){kind=icon}
 "Alien 3"){kind=icon}
 "Paladog"){kind=icon}
 "Canyon Defense 2"){kind=icon}
 "Tower Force"){kind=icon}
 "Robots vs Zombi"){kind=icon}
 "Excit"){kind=icon}
 "Epic War 5"){kind=icon}