1. Which stage did you stop at, and what made you stop — too hard, too repetitive, or just bored?: Stopped on stage 8. I just stopped to continue working on my game
2. Did the touch controls feel right on your device? (Which phone?): Played on computer, so can't answer this question. Computer controls felt right
3. Stage 5 is the first real boss. Does it feel fair now, or still unfair?: It feels fair. However, on stage ~7, 2 bosses overlapped for a few seconds.
I would like a popup about the shop with candy coins at the end of each level.
For future reference, using "50 stages, no ads, no gacha, works offline" for promotion is too general. The first sentence should basically be the title.
Balancing: Lv2 donut shield is op, the orbit weapon is far underpowered, the goo weapon is overpowered, and heart regen needs a light buff. Heart chest should give gem overload at full hearts. For the first ~4 stages, damage buffs were almost useless, as every non-boss would be one hitted from the start. Upgrades on main weapon should show the increase in damage. There is no way I could complete stage 20 with the difficulty scaling.
I also did not use nuke, as I could not reach for it on computer fast enough. Please make a button for the nuke.
"I'm building this to be something kids can play": This is successful at that.
"Happy to return the favour — drop a link to yours and I'll play it and write you something specific back.": I will come back next week for this, as I'm in active development of my next huge update.