I have a friend in a couple of my role-playing groups who just isn't enjoying the games very much. (We are currently running Exodus in one campaign and an D&D retro clone in the other.) This player is in their late 20s and started playing RPGs about a year ago. They play other card and board games with us as well, and seem to enjoy them. (Things like Magic, Small World, Munchkin, etc.)
Both of our games are very casual; there's lots of joking and laughing. They very much enjoy the social aspect of playing RPGs: sitting around and talking/BSing with friends. They also tend to get more involved during combat and skill checks, i.e. any time there is dice rolling involved.
The role-playing is another story. They will say the minimum required by the story, like a "Yes" or a "No" to accept a quest. Because they seem to be uncomfortable with it, we haven't pushed them into trying to "come out of their shell" more, but we still make sure that they have spotlight time. We definitely enjoy having them as a player.
I've talked to the player about this, to see if there's anything we can do to make the game more enjoyable for them. They stated that they have "very little imagination", even going back to childhood. They talked about playing pretend with siblings and friends and just not knowing what to do. They have mild Asperger's syndrome, which may be coming to play here. (I say "may" because I just don't know.)
I have a great imagination so I'm not sure how much imagination is needed to enjoy an RPG. How do we help this player enjoy the games more, so it's not a chore to play with us?