the basic idea in awesome, and it works incredibly well for the first minutes. However, after a while the game gets quite repetitive
I'd suggest adding more elements, like new patterns for the ship or new enemies, that could pop up in the advanced waves. the ability to upgrade the ship would be interesting, what about upgrades that reduce the % of a "bad mutation" or increase the % of a good mutation?
This game has a lot of potential, I really hope you continue developing it!