Pretty good! It was fun, and that's the most important part.

If there is no penalty to simply shooting all the time, then there is no reason to not shoot. To solve this, you can A) make the player shoot unconditionally or B) provide a downside to shooting (e.g. slower movement speed). Most new devs (including myself in the past) don't realize the importance of decisions in games. This video should help.

Since I made only some 290 points in the first round, I think it would be a good idea to lower the prices of the upgrades so that players can actually use them often - this adds another decision to the game.