I think the gameplay is solid. However few things I would change.
- Audio gets a little annoying with time. Maybe make this adaptive, so the audio changes when the certain in game milestones are reached. Potentially after reaching a certain value money wise, or a bomb getting close to the ship
- The waves are very rigid, and are very noticeably a single sprite.
- Tutorial/instructions is a wall of text. I got very overwhelmed by it, Reading is for nerds... So didn't read and just pressed spacebar lol... Also, maybe get rid of the prompt of "Use spacebar to use radar" once the player has used the radar, as I understood that was what it did, pretty much immediately.
Could make a simple iOS/Android game, if you made it so the cash you collect you can buy skins/upgrades. it would add some replayablity. Could monetize it with ads on game start/between levels.
Solid foundation, well done, keep it up!