Can PS3 games work for ps2 games?

No, PS3 games will not work in a PS2. Fit is not the problem. The PS3 games are not able to be "read" by a PS2 machine just like you can not play a Blu-ray Disc in a DVD player even though it will fit in the slot. The reason the Disc will fit is so the PS3 can play DVD's and up scale them to HD quality and that is why they did not make Blu Ray discs a different size from DVDs.