I've been playing this daily for a while. The issue I've found with it is that your health recharges every 100 steps. This creates a divergence between the fun way to play and the way most likely to win. The optimal strategy is to spend a long time button mashing between enemies, and to run back and forth for ages when facing a powerful enemy. I think it would be better if your health didn't recharge (with the enemies rebalanced to accommodate this). This would force the player to actually make smart decisions.