Can you recommend an appropriate xbox 360 game for an 8 year old who really wants Halo and is not allowed to have it at his age.

You could try "Rayman: Raving Rabbids". My younger sister got it when she was about 9; it's a good game for younger kids if you don't mind indulging them with "potty humor". It is rated "E" and there is some carnival style shooting which should satisfy his need to shoot things (nothing too violent though as you only shoot plungers at rabbit-like creatures when they pop up). I'd say it is much more appropriate than "Halo" for en 8 year old (although I must admit it is a ton of fun). This game mainly consists of mini games which are loosely based around a story line but if he is looking for a game with a plot then I would choose something else.