Power cards have a maximum level (5) while equipment cards can raise to level 10. So the mana costs will not raise forever. Still the game balance is totally off.
To finish it fast focus scouts and dreadnought (after a while buy 100 of the other types), ascend when you double your PPI amount and repeat. After the whole galaxy is yours the game ends...
2 Costumes are missing: in the last level there is a guy with a black coat and glasses behind "superwoman" and the yellow mask dude over the mario bros. Please add them :)
Animation is too slow, too much grinding for exp while gold is basically useless since midgame. Still a good game so why don't you polish it a bit to make it a really good one? :)