Comment by aidenn0
I suspect many PS2 games were mostly written in C or C++, which greatly simplifies things. Games that used the interface libraries from Sony for e.g. managing input will greatly simplify things as well.
One notable exception is the Jak and Daxter games, which were written in GOAL[1], but have their own recompilation project.
1: https://en.wikipedia.org/wiki/Game_Oriented_Assembly_Lisp