Update 220306

New: Combos. Successive killing enemies without taking damage ticks the combo count on the top right, and every 50 combo increases the score multiplier by 1. e.g. at 0 combo, the score multiplier is 1, but at 120 combo the multiplier is 3. Since all non-boss enemies have default score of 1, this effectively becomes the score per enemy.
New: High scores. The previous versions didn't need it because of the limited number of enemies with no multiplier, which set a ceiling for how high the score can get and pretty much every successful run would give score in the ballpark range between 1200-1300. Since that's not the case anymore, a high-score system is added. The score will be red when you're over the current high-score, and you'll see the current high score for each character on the title screen.
New: Progress percentage on the bottom right. It shows how close you're to finishing the game, which I think would be helpful as there's no stage division and little visual change as the game progresses.

I didn't set a cap for the score. The combo is capped at 999, and you'd need to kill 1,608 enemies with the max combo multiplier of 20 to reach 32167 and there aren't enough enemies to do so, making the overflow extremely unlikely.
This still isn't the kind of game for the high-score competition in the traditional sense due to the randomized nature which would affect the end result, but it could still be an incentive of sort to make an effort to dodge bullets. At least I know I didn't bother dodging boss bullets when I was sitting on 50+ shields.
Update 220214