Had fun playing this! Got around 3500 points once. It's really hectic, which is fun once you kinda understand the game. I think that it starts off a little aggressive at the jump, and without sacrificing any of the frantic lategame it could be nice to have a minute to get my bearings, earn some currency and set up units while enemies trickle in before the flood. Especially as a first time player it can be a bit demoralizing how quickly you get overwhelmed.
A think the interface has a few small problems as well, small easy to fix things but that hurt my trust in the reliability of the controls and made the game harder to play, particularly when overwhelmed by a lot of units.
Being unable to select a unit type if you don't have enough currency feels likes a bad choice. When i'm waiting for currency to trickle in I often want to switch to the unit i plan to place down in anticipation for placing it, but since it doesn't allow me I often ended up putting down the wrong unit and wasting my money at a critical juncture.
A smidge of feedback would be nice as well for hovering/placing units. Perhaps a ghost of the unit selected so that I know with confidence what i'm about to place, and some small sounds when i select 1-6 with different pitches so I know what I have selected without looking, and another small sound when clicking that confirms or denys that a unit has been placed successfully so that in the middle of a frantic situation I waste less time in insecurity.
Either way it's good fun for something so simple. Haven't seen a tower defense with a radial layout like this.