I'm a big fan of the PS2 games Katamari Damacy and I [heart] Katamari. It occurs to me, particularly in the sequel, the game is filled with characters egging you on and challenging you to do well. Other games, such the Pokemon RPG games, also have lot of characters that reinforce the notion that what you're doing is worthwhile. I think more games, particularly American games, could stand to have a bit more of that. When I'm spending hours at a time collecting arbitrarily large quantities of gems, or sparkles, or whatever, the more NPCs that come over and tell me how great I am for doing all this work, the better.
-Adam!!!