Appreciate you actually playing through 8 stages — that's more signal than most feedback I get. A few updates based on this:
The boss overlap around stage 7 was a real bug, not just visual noise — the health bar was getting handed to whichever boss spawned last, even while the first one was still alive. Fixed.
The upgrade card damage numbers were worse than you described — they weren't just missing the increase, they were frozen at level 1 forever regardless of your actual weapon level. Also fixed, and the orbit weapon's card now shows a damage number at all (it didn't before).
Nuke now has a keyboard shortcut (E) for exactly the reason you hit — reaching for a screen button mid-fight on keyboard/mouse doesn't work.
Good note on the store page — leading with the title instead of the feature list makes sense, I'll fix that copy.
On the balance points (donut shield, orbit weapon, goo weapon, heart regen, early-game damage buffs, stage 20) — I'm not dismissing them, but I don't want to retune numbers off one playthrough without a way to A/B test it properly first, so these are noted and queued rather than acted on immediately.
Glad it's landing as something a kid can actually play. Take your time on your own update — I'll take you up on the offer to swap links when you're back.