AdriPSX is a relatively new emulator which was first released in December 1999. Although it lags behind PSEmu Pro (and commercial emulators like Bleem and VGS) quite a bit, it's already able to emulate a few games.
And unlike PSEmu Pro, AdriPSX is still actively developed. AdriPSX is a promising emulator. However don't expect it to run your favorite games perfect yet or even at all.
