Bully, (but the version I had was called canis caem and edit, they are both the exact same game), is a game made by rockstar, the same people who brought you gta san andreas! And you do notice that whilst playing this game, as the two games feel very similar, and this is not a bad thing!
Anyway, in this game, you play as the school bully, in a sort of free to roam mission based world, where you have "quests" and classes to be getting on with, along with a bit of mischief. The way the game basically works is that by going to classes, you learn skills (for exmaple, in gym wrestling class, you learn new combos to use in fights). You can try to avoid classes, but if you get caught (either by a prefect, or a teacher), you will be sent to the class (and I think you may lose points, it has been a while). On top of this, you must collect "weapons", like fireworks, stink bombs, catapult pellets etc.
You can also get "notority" for causing mischief, and kissing girls, and things like this. Furthermore, you can also do some "good deeds" for people, but people will think you are getting weak if you do too many of these. Note if a prefect sees you doing something you shouldn't or if you are out of your dorm after dark, they will chase you and try to beat you up! But you almost cannot fight them off, they are way bigger than you.
Furthermore, there are "gangs" of students. Don't expect to be able to run up and punch 1 person in the face without his friends reacting in some way, its really cool, and doesn't feel like it gets old. Its actually done really very well. Also various areas of the school are "owned" by certain groups, like the math classes full of geeks, the sports field full of jocks and so on. Each "class" has different attributes, like the geeks are easy to take in a fight, whereas the jocks aren't but the geeks are more likely to be your friend, or help with homework and so on.
Anyway, overall, this is a pretty good, game, but it does get a bit boring over a period of time. The plot is funny and good, but I feel I cannot give this game 5/5 stars, for reasons I am not totally sure about myself. I mean everything is there, good plot, decent graphics for its age, good dynamics, but there is something missing from this game making it unmissable... Maybe its the fact you can't fight off prefects. Maybe its the fact there is no real problem if you miss classes or get knocked out. I am not sure...