One of the upgrades literally gives you one frame of advantage? Some people might like trying to be accurate up to .05 of a second but such low forgiveness isn't for me. It doesn't become fun anymore because I know that being that accurate over a long period of time is less about skill and more about rolling your reaction time luck.
However this game is extremely well made and all of the monsters are well drawn, well animated, and consistent, if not for the unfair frame-perfect requirements. It runs well and there was a lot of time put into this. It just ain't for me. A bitter five stars and a middle finger to the ancient ghost.