So why do some games work and others don't?

I just got an Nvidia shield and it brought back my interested in emulation, specifically PS1 emulation. I use FPSe and it works great, but some games refuse to boot and cause it to load directly into the bios. I just want to understand why this is happening, is it something related to FPSe? Is it the game itself? I tried multiple BIOS's for said games and it just won't boot up the game at all.

Example: Team Buddies and MGSx work fine, yet theme hospital and the UK version of team buddies don't no matter which BIOS file I try.

It would be related to FPSe I believe, although it's part both working together. These games might not be compatible with the version you have, or all versions of the emulator in question, I believe this compatibility list might help you, I'm not sure if their is an official one anywhere since I've never used FPSe. http://www.roms4droid.com/index.php/...tibility-list/

Thank you so much for the reply, I actually just found out what the problem was, it was a very stupid one on my end. Basically I did not realize what ECM extention was and since I was downloading them directly onto my device I just renamed it and removed that thinking it would work. Thankfully I figured it out and now the ones that don't work seem to be working fine.