I searched the forums and was unable to find an answer, but anyway. I'm using the latest version of ePSXe, and the game runs smoothly and everything, but there's one small problem: the rhythm just doesn't sync with the game at all. I have to purposefully hit the buttons a second (or half a second) after I really am supposed to press them, so technically, it is possible to complete the game, but I have to be off-sync. Any ways to fix this? Thanks.
To tell you the truth...playing the game on a real ps1 is exactly the same. I was just playing this game about a week ago, and I noticed the same thing (but on a real ps1). I think that you are actually supposed to hit it right after it passes the "hit" marker (and pushing that button as many times as you can before the next marker is reached should raise you score). I found that to work best, but like I said, it is pretty much the same as on the real ps1.
The weird thing about Parappa is that sometimes that method I described works, sometimes it just doesn't. The funny thing is that when I actually tried to play along with the beat, I lost the level over and over again. So I got frustrated on the fourth level I believe, and just started pushing random buttons the whole time the song play... And for some reason it gave me a "Good" rating and let me pass the level! I don't think the game was very well made to begin with, and unfortunately only lasts about 40mins or so... Still a fun game though.