Should keep track of each level finished, how many hearts remaining, and how many steps taken. Can use that to score the level.

Very nice game! But, as bluecrimson said, it is too easy. Would love to see sequel.

Simple but addictive! Love the music, catchy as hell! Enemies become a little boring after awhile but that doesnt take away from the fun.

It was pretty fun, but it wasn't really challenging. It became more about removing the weapons that could only be used on one enemy. The few that might have remained could then be removed with sufficient health.

To improve the difficulty, you'll need to have more weapons that could potentially kill more than one enemy. The last level was probably the best representation of this. But with more choices, it would also be more annoying if you screw up and need to start again from the start. So, you could add an undo button to help remedy that. It might also be worth acknowledging successfully killing all the enemies without losing any HP.