Desperately needs one of two things: 1) the ability to reply older levels and grind, and 2) a SAVE system. Actually, both will be essential for you to get a good rating for this game.
don't feel like searching comments tosee if this has been suggested, but hitting the objects is actually integral to winning. You can use them to keep speed down. This avoids overjumping buildings and missing glass windows.
I agree with Jkaa below. The game is fun, but still too slow. The enemy move speed should be raised a bit more, but most importantly, make the exp numbers pop up at the instant the hit connects, and eliminate the darkened screen. Waiting for the screen to darken is a nice stylistic touch, but it makes players feel like their time is being wasted. When that happens, it isn't a game anymore, it's a chore.
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you can play old levels by clicking them on the level list, and the progress is now saved :)