Comparing profile between users, then suggesting whatever isn't in your current wishlist.
Step 1 : Get my wishlist
Step 2 : Compare it to other user based on number of shared wishlisted/owned game
Step 3 : set a timer like the steam synching to reduce loads on server when comparing multiples user wishlist
Step 3.5 : can sort trough user by comparing type of game first ( action , rpg ... ), then per games
Step 4 : Compare to multiple user based on % of similarity, then pool the games that i haven't wish listed but are in similar user and count them
Step 5 : Recommend the games that are the most wishlisted by similar profile, that you currently dont have in wishlist