I will say that I'm happy with the first 4 levels I made as their great introduction to the game logic, but I do admit the rest could have more work done on them. What makes it challenging is that it's the angle + position as you don't want to get hit but your trying to make your doppel get as well.
I also have to say the level where you decide who gets what weapon is another favorite as that leaves the decision up to the player. The second to last level (rocket launchers) is probably thee hardest one to beat. If I continue work on this game I'd definitely do more play testing and fine tuning the challenges with the levels to better introduce the weapons and concepts. 👍