Need help on Xbox games rated T or under

My son (11) has a new Xbox but mom has lowered the banhammer and he is not permitted to play any rated M games. Naturally those are the ones all his friends play. Personally I wouldn’t have a problem with a game like Halo to name one hot title in particular but there are some (Call of Duty, Modern Warfare - gritty, modern, realistic, graphic) that I probably would want to hold the line for an 11 year old. Anyways…

What are some good titles in either the Action / FPS or the Fantasy / RPG genre for the Xbox to get him plugged in to? So far we have found two that he likes (one’s a LOTR title and one’s a James Bond) but both appear to be short on replay value and neither are supported by the Xbox Live servers anymore.

Don’t have to be new titles (in fact would prefer some that are not and so cost only $20 or $30) - but in the FPS or RPG style is preferred and with multiplayer is preferred - moreso if he can play on XBL - above all replay-ability.

Thanks in advance Hivemind and a very, merry Xmas.