Yeah, it's missing a lot of polish and the audio is pretty bad (both the lack of music and the gun sound effect is somewhat jarring).
I would also have liked to either have proper levels, or procedurally generated arena. The entire "expanding arena" mechanic was simply because I didn't have time to implement multiple levels and it was the simplest solution I could think of.
To be honest I probably didn't spend enough time on the game. Over the 3 weeks available dev time I probably spent less than 50 hours on it (including design and prototypes). If I were a first year student I'd probably have twice as a long, but I was extremely busy with uni work. At the least it would've been some good experience with Unity even if I hadn't won.