I noticed you in the leaderboards this morning, congrats on finishing the game (twice!). That's impressive.
Though I might reset the leaderboards on 15 January to time up with the Steam release, but I'm not sure yet. I hope you don't mind, otherwise let me know I can get you back in there.
Thank you for taking your time to write your opinion about the game. Though I can't reply to all your points, I still hear you loud and clear!
The point you mentioned about button-mashing and aircraft speed had polarizing opinions throughout development. For example at first the aircraft had an overheating mechanic that many disliked, so I had to come up with an incentive for the player to ease down shooting over time, that's when I thought of button-mashing + slowing down the aircraft while in fire mode.
The charge shot while holding down the fire button was in my to-do list as well, though out of laziness never got around implementing it.
Aircraft speed is super slow indeed, I realized that quite late into development. By then I couldn't increase it as that would entail redesigning many enemy-behaviors that rely on the player's speed (like the Ranger in Area 2, Bomber/Area 1, Crusher-doors/Area 4, and many others). Though in a way I'm glad I kept it this slow, you get used to it pretty fast and the gameplay feels tighter and more precise akin to that of Guxt, my main inspiration gameplay-wise.
The other shortcomings about bosses are absolutely true, I reckon most of them need tweaking, and I also find myself struggling with the 2nd phase of Boss 1 more than the 1st phase of Boss 5 for example. They're still challenging neverthless, so I think that's good enough for a perma-death shmup.
The achievement popup scare the heck out of me, they're kinda loud and spontaneous, but I think that adds up to the surprise of having unlocked an achievement :) I could fix the Detonating Shooter popup by making it trigger a little later on. I'll add it to my to-do list, eventually this could get fixed.
I'll look into those bugs right now. It's strange I can't seem to turn off fullscreen either when I tried it just now. Thanks for the heads-up! Will look into this now.