I think it depends strongly on the upgrades you get. My second playthrough went very differently and was more fun and satisfying because I had the ion blast (see second edit of my comment) and, I mean, it has to end at some point. Maybe there could be some sort of ending or something, so it doesn't feel like the game gets unfair at the end or something, but that would probably be out of the scope of a jam. Regardless, an outstanding game (with the ion blast ;)).