This was fun :)
It seems obviously a little stuck together with duct tape and lacking polish, but the variety of enemies is nice, they way they're introduced through the scenery is really nice.
Constructive (hopefully) feedback, as a shmup fan (but I still suck at them so take w/ a grain of salt):
- Keyboard controls don't feel good - typically anything other than precise digital control (e.g. introducing friction/inertia) is a cadinal sin (apart from MAYBE in Risk System... maybe)
- Audio levels aren't balanced, Stage 2 boss music hit me like a truck
- More telegraphing, VFX, polish in general for the columns that appear in the tunnels would be great - for a while I thought they just instantly popped in before I realised they do "appear" through scaling(?). Have dust kicked up from them or something? ZeroRanger does this nicely in Stage 2 with horizontal blocks, for reference
- Quite a few times I didn't realise I'd destroyed an enemy, as I didn't notice the subtle darken right away. Some tasteful VFX would do well here, and maybe something different with the sprite? E.g. have "airship" enemies get their balloon popped instead of the "belly-up" animation
- Some VFX, animation, in general some feeling of "impact" when heavier ground cannons fire their shots - muzzle flash/smoke VFX, or the enemies recoiling, or all of the above?
- Enemy missiles following me looked weird when their rotation didn't change once I moved behind them