Wow, I ended up playing this for a lot longer than I expected! This was really enjoyable and the difficulty curve was nicely tuned. Levels 3-5 are especially well-calibrated so that you need to buy just the right types of ships and really need to think about group composition rather than just spamming buttons. I know TD games can be quite difficult to balance and test during a short jam, but you did admirably and the final product is quite impressive! Also, very nice work on the smoke, muzzle flashes, and various other particle effects - looks great :)