Wow, this was really fun to beat!
It took me a few tries to realise I could actually get drops from enemies, but it was all uphill from then. It also took me a long time to realise there was actually a time limit!
I'm really impressed that you managed to put this all together and get it working within the jam limit. Well done.
I definitely see the Vampire Survivors inspiration, but I really appreciated that you gave the player agency in deciding when it was time to progress to more challenging lands, rather than having progressively more difficult waves forced upon you whether you're ready or not.
The different regions were really cool, each with their own enemies and music, even though I spent most of my successful playthrough scared to venture far into many of them!
Also, this might just be me, but the music for an area far to the right (desert or beach I think?) kept making me jump whenever it started, haha. Something about the trumpet-y instruments made my brain think it was a vibration or a phone buzzing or something, I think. It was pretty funny, and added a bit of an extra adrenaline rush whenever I accidentally ventured there and the music startled me. Fun times!
After a while, I felt like it might've been helpful to perhaps see the total sum of stat points on each weapon, just to help quick comparisons (but then again, maybe not all different stats are equal). It'd also be fun just to keep playing, and see how crazy one's weapon collection can get. :)
The fact that you not only implemented waves of different types of enemies, regions, drops, a stat system but also a fully functioning boss battle is just incredible.
Overall, this is extremely impressive. I really enjoyed collecting equipment, comparing stats, upgrading, and seeing my collection of weapons wreak havoc. Well done!
P.S. I love your planned idea of having the main character's son carry on the quest. I had a lot of fun playing Rogue Legacy! (I never did quite manage to beat it, but I came close)