Really good time-waster, though while the constant feeling of progression makes it quite addictive it also becomes repetitive quickly. Especially once you realize that staying on the middle platform in the first level makes aiming a lot easier.

The main variation comes from the many weapons, as there are only 3 enemy types and the difficulty does not increase during the game. Most weapons are quite interesting, though there are also a few that are too similar to each other.

Even though you can buy new weapons in the shop, it is unclear what their characteristics are. I would at least display their names to give a hint. If the large amount of weapons in the shop gives choice fatigue you can always reduce the number of options (e.g. new weapons become purchasable only once you've bought a certain amount).

Buying new weapons also increases the maximum multiplier, though tbh I never reached beyond 6 anyways. What I do like is that picking up weapons increases your multiplier, which makes it feel as a choice even though you're always going to grab it for the multiplier even if you don't like the weapon. If you fail to pick up the weapon before it fades away however, it decreases your multiplier which adds a nice bit of urgency.

The small level also adds urgency. If you let only one enemy pass you want to take it out asap, which means neglecting new enemies that can also pass you, rinse & repeat. Chaos guaranteed. Because you'll constantly be in chaos, it is a shame though that you can't easily see the amount of remaining hits the dynamo can take. I would add hearts or something, instead of a health bar.

The game also looks & sounds fairly good (the screen shake can be a bit excessive though), especially the start menu is dynamic & funny. So I'm curious, how did you make the art?