strange how no one mentioned cod4.
my advice is oblivion, cod4 and orange box.
assasin's creed is hyped and it takes a calculator to count the technical issues. it doesnt score too well either on gamerankings.com
fall of man is old solid launch title and the graphics is just average. also, it has a cliff hanger ending.
ninja gaiden is actually sort of a remake of the xbox ninja gaiden black, so dont buy if you are not that interested.
lair is not worth mentioning, clumpsy controls and dull gameplay. though some reported the control has been improved after a patch.
all in all, you should wait for the orange box.
buy cod4 which offers a relatively short but exciting sigle player campaign but makes up for it with a deep online multiplayer which combines rpg elements and once again, online service is FREE.
buy oblivion which has been an instant classic, so no need advertise. just one thing tho, make sure you get the game of the year edition.
it is a shame that you bought a ps3 cos you miss out mass effect and bioshock.
ps:dont understand why you would get a underdog console.