cod mw2 is a first person war game.

ac2 is a fun but challenging 3rd person medevil game about being an assassin with a power call 'eagle vision'

cs:go is a pretty challenging game and requires tactics instead of run and gun stratigies

unturned is a fun free zombie game, most people say it is the baby of minecraft and dayz

tf2 is a fun free steam game with an awesome community