The 7th wave is the last one right? I always die there but I think sometimes quite some time after I reached it. Defeating all the aliens is super hard, I don't know if it's technically doable or not. I don't know how much getting hit on purpose is intended or not either, I think it's fine either way anyway.
This game is very fun, the half of an enemy blinking when you're hitting it feels so much NES, that was really a super good idea. The game sounds good, I like the design of the aliens and it mostly plays like a NES game with the appropriate speeds of everything and the right amount of things happening on the screen.
A 2 player mode is a very nice touch, I've not tried past launching a game so I don't how I feel about each ship being stuck on its side instead of simply crossing each other, it seemed unusual but it might be perfectly fine in practice.