Thank you for the feedback. Yes, the predefined waves are a feature, I was inspired by R-Type in that: after a while you could do it blindfolded... until you screw up and need to start to dodge bullets like hell!
Another thing I noticed is that, in one of the last tweaks, the enemy bullet lifespan is too short they disappear way before reaching the edge of the screen and so the safe area is much greater than intended. I didn't tought of the angles, in fact those are too safe.
In the end all the waves needs to be redesigned: way less bullets, more tricky situations.