Man, what a great game!! It was engaging, funny, witty, really fun, and very well thought out! the mechanics seemed simple in isolation but had a lot depth as a whole. Took me 4 long tries to beat it, the first time I lost at chapter 8, just before the reveal! I was really engaged so I had to retry, the next time I lost to the final boss, just when I was worrying it was gonna be too easy the boss did that thing where it "hid" and spawned zombies, healed, and when I was about to beat it it just did it again but this time it spawned wayyyy more zombies!! ended up getting cornered and killed. Third try I didn't make it to the final boss due to poor choice of upgrades (only one rack, got cornered again). Fourth try I ended up beating it before the boss could summon anything! I was a little disappointed there was no ending sequence, but all in all this was still an awesome experience.
Awesome game! had a really fun time playing. The only thing I would add is some way to heal in chapter 8/9 when upgrades are no longer available.