What a great idea! I did this same sort of thing for my husband when he turned 25, and he LOVED it! I contacted all of his old friends and a few good new friends--he was so busy "catching up" that a bunch of new friends would have felt neglected. All I did, seriously, was create a spread of tons of awesome "game" foods, and invited the friends! That created a great party. Music could be cool too.
Another Hugely Successful and memorable idea is: in the invitations, include a blank card, and encourage the guests--even those who can't make it to the party--to write down something. For instance, what they like about the birthday boy, a scripture verse he emmulates, a memorable occasion, a note of appreciation for something he did, etc.
Have many more cards on hand at the party, because most of them will forget theirs at home. Have the birthday boy decorate a paper lunch bag (okay, so we did this in college. My husband still has and looks at his.) however he likes with crayons and markers--it's fun! not tacky in the least!--and when the guests arrive, have them fill the bag (or whatever recepticle you choose)with the inspirational thoughts and quotes and verses.
For food I made Baked Ziti, Green Salad with Dressing, Layered Nachos dip (cream cheese, refried beans, salsa, shredded lettuce, tomatoes, cheese, etc.) with Tortilla chips, Hot wings, potato chips, trail mix, fruit salad and then dessert and lots of drinks. Whew! It makes me tired and hungry thinking of making all that food! :)
Good luck!
~A.