Hey mate. First off, thanks off for the detailed and constructive criticism and playing and liking my little game.
I admit that the whole background collision detection thing is kind of the "weak point" of the game. I settled early on for a system that is super fast and reasonably effective, but might be a bit too unprecise for what people expect from a SHMUP, unfortunately. I will certainly improve on that the most for my next game, I promise!
On your points:
1) Hmm, no idea on that. Hope it's playable anyway ;)
2) That intentional. You cannot hurt him, you just have to wait for a certain amount of time passing.
3) I haven't encountered that myself. If you find or can record a video of that happening, it would be helpful. :)
4) Funny, didn't notice that myself. The bullets won't hurt you after explosion sequence starts, though. Maybe that's a little consolation.. haha
5) Yep, that unfortunately comes a bit along with the fast but a bit unprecise system I used for my collission detection. With these organic designs that flaw gets even a bit more obvious. I can only recommend to do "probe shots" in the direction you wanna go to check out of there is a wall there or not in the collission map. Usually I went for less collisions areas when in doubt.
Thanks for the feedback and kind words, mate.
Hope to improve on that stuff in my next game.
Also, watch out, I will add another level to the game to download for free. Will take me a month or two to create, though..
Greets,
Michael/Tigerskunk