well if u have a ps2 with a no solder chip or flip top theres alot of games that u wont be able to play vist
www.swapmagicfix.com for that list
if ur useing a apple mod chip or any older chip theres a few games that u wont be able to play EXP splinter cell, true crime, S.W.A.T, freedom figheters
if ur use a new mod like duo magic V dms3 only a few games will give u probs there not relly protected there just dvd9 so u will have to rip them which can be tricky to any newbe
metal gear solid 2
xenosaga
champoins of noroth
i belive those r the only dvd9 out but there could be more but other then all that theres not relly any protected games out there