The creativity takes the cake on this one to me!
Because of the static nature of the enemies, the game doesn't have that sense of constant danger that bullet hells tend to have. In fact, this played more like a puzzle to me - which was a nice surprise, in fact!
Art and audio aren't great but that's understandable given this is a solo game that uses asset pack stuff. Everything felt well implemented, though, particularly in the transitions - both visually and in audio, the game start and the teleport transitions are pretty smooth and work pretty well.
The Arena looked like a Petri dish to me for some reason, so going in I expected this to be a game about bacteria or nanobots! Nonetheless, the circular arena does a nice job of making the player feel confined particularly due to the reflective walls and how those interact with the bullet paths.
In fact, random spray from moving in and out of bullet paths was the one thing that really gave me danger since in some cases the bullets can spread around very chaotically and still be around when your shield depletes. However, patience and careful thinking got me through the game safely!