You really captured the feel of a battle arena! Right off the bat, the enemies were fast and dangerous. I really felt like I was scrapping for my life in the first round.
I like the city/urban tileset goes a long way toward setting the tone of the game. Obviously, this isn't a story-driven game, but I am definitely intrigued by this world and the monsters populating it.
The enemies did have a few pathfinding issues moving around corners, but the manic tilting animation makes them feel rabid and hungry, so the semi-blind charge toward the player actually feels appropriate.
I watched Kevin play this on-stream, so I was only planning to play for a few minutes, but this is a really addictive game loop! I told myself "one more level" more than once so I could take just one more upgrade.