Thank you for your feedback!
There are already some plans in the works for the unfair planet system.
It's true the Invisibility, Multishot upgrades are a little unclear on energy consumption and the 50% more credits is a bit overpowered, these will be fixed in the patch.
As for the balance, I designed it kinda like a casino, the first few attempts are a struggle but once things get going... they really get going!