Just some notes I made while playing.
The hit boxes are pretty small especially on mummies.
Pyramid boss medal and beyond doesn't unlock.
Traps felt fairly useless except against the brain kamikaze guys, I noticed traps block shots maybe making it so they block more than one shot would make them more effective.
Consider adding different currency for additional items, you do get enough to buy all upgrades but wasting credits on ammo, early on, seems like a bad idea considering how the difficulty ramps up each level, although the stock is so low buying doesn't really matter and pickups are plentiful.
How many rooms "are a lot" of secret rooms?
How many unused credits are "a lot" of unused credits?
No pause button.
Health bar is large and hard to tell how much you have at a glance especially with enemies kamikazeing at you its hard to tell if you're wasting heath pickups.
Whats wild at heartness I see no button in the description for it but its in the shop.
Level 4 was way too tough even on easy with all upgrades there is so many enemies and the pink guy that shoots multiple projectiles pretty much just overwhelms you even at full health, level selection would be a nice feature it just feels overwhelming to go through these fairly large levels again just to get to level 4 again.