The speed kill system is horrible especially on the last boss. I know that I'm supposed to wait for the sword flash when speed killing but sometimes it just does not flash. This becomes infinitely ridiculous when the last boss involves 3 groups of speed kills. I finally had to give up because it just doesn't work and it is not worth wasting my time on. I'm very glad I rented this and didn't buy it. I thought it was because I wasn't waiting long enough or I was not still enough but that is not the case. It is just a very frustrating glitch that ultimately ruins what was a slightly better than average game overall.