Resistance 1 & 2, Unreal Tournament 3, The Orange Box are quite Science fiction (all of them are about alien invasions). The others might be too, but I’m not familiar with them (that feels good to say for a change).
Uncharted 1 & 2 seem to be quite popular for the ps3 (here’s some gameplay). It’s more a mix of a platform game (crossing obstacles), some puzzles and bad guys (which you can shoot of course). The slower pace of the game combined with the added puzzles might make for a nice change (Modern Warfare is a great choice, but you don’t only want to give him games that are clones).
You definitely want to put some games in there as there is nothing worse than getting a cool present with no batteries (and the stores are closed). Just make sure he can return them if he doesn’t like them.