It's too easy to upgrate yourself to the fullest, by playing level 1 over and over again, investing the money into the health of your crew members. And then there is no challenge to get all the awards and rewards.
==> 1. Set a max money limit, which one can get by playing on section, so you wont be owerpowered
==> 2. Upgrate not only the health of the enemys, but let them use the really powerfull weapons, not only bazooka and mine
==> 3. Set a platinum Star by beating the planets in a VERY low, nearly impossible numbers of turns. In later levels, you often can beat them in 8 turns, you just have 4 turns left for gold...
==> 4. The "Rockets-of-the-Wormhole"-Weapon ist hard to lunch (bug?)
First: The KILL ALL ENEMIES ON SCREEN should count as a multiplyer!
Second: Why not make a badge Score 3000 points without killing one enemy are that like... well i think there is actually no need to add badges, i will play this game anyway