I just played Splinter Cell :CT at my friends house on the co-op mode and I gotta say.......it's almost better than Halo(1or2). Two Sam Fishers creeping around, getting into trouble is just so much fun! The co-op help options are a big part of the fun: Climbing each other like human ladders, tossing one another over walls/at enemies, send ing a rappel rope down to your ground bound ally. The teamwork fun never ends. We set up all kinds of traps and systems for getting through the level like one of us watching over a courtyard(look out) while the other stalks about killing the enemies, luring enemies into the waiting hands of our hidden ally, and funnest of all, both of us killing off two guys next to each other at the same time so that the others horrible dead doesn't alert the other guy......cause he's already dead too!
We only played one level, and set off like 50 alarms, but it was too fun to care. Once we learn some of the more subtle tricks of the game me and my pal will be killing terrorist left right and center!
Bye the way, watching your ally creep up on an unsuspecting enemy and take him out is COOL!