This was well-scoped for the game, and its balancing scales surprisingly well!

I had some weird stuff where my character was moving around as though something was pushing it, but there weren't any enemies nearby - as though there were some physics colliders left behind after an enemy was killed. I was also able to walk (or get pushed) outside the viewport, which allowed me to get attacked by stuff I couldn't see.

I survived for 900 or so seconds before I eventually disappeared off the screen. Across that time, the game scaled well to match my upgrades and never had me feeling overpowered or underpowered while still keeping thing after 15 minutes as they were at the beginning of the game. While I don't really have much genre literacy, I feel like this is the key design challenge of these types of games, and it was well executed here.

I think it would have been nice to have some audio - even if it was just ambient sound or music (finding the right intensity for sound effects in a game where enemies, projectiles, attacks, etc. scale up to huge quantities is another challenge, for sure!).

All in all, a little lacklustre on the presentation side, but definitely impressed me from a gameplay perspective. It's also always nice to see submissions with sources available. Well done!