ryryguy
First Post
It's really hard to be sympathetic to such a player, so much so that I'm not even going to try. Honestly, if you really want to cater to his loner attitude you should be DMing a solo game for him. Myself, I'd tell him to go play video games. D&D has always been a team game, so it's not like this should be a surprise to him.
I'll try to summon some sympathy for this player on your behalf.

I had an experience similar to this with the loner player I described earlier. He tended to be this sort of powergamer playing alongside largely inept and newbie players. The other players and DM didn't really have enough system mastery to match him or deal with him. The thing is, he's one of the best players around when we aren't in a competitive or tactical situation. When I joined, our games largely became an arms race, as I had the ability to match him in system mastery, and it bothered me that he dominated the game to the extent he did. I powergamed in response, and began powergaming everyone else's characters on their behalf. At that point, we had powergamed beyond our DM's ability to deal with the game. I became the full time DM at this point.
I don't think enjoying system mastery is an invalid play style; thus, I can summon some sympathy for this player now feeling a bit adrift.
At the same time, it can lead to the sort of unbalanced situation casualoblivion describes above and various others have decried in this thread. Spotlight hogging and all that. Generally, that is not fun for the rest of the group, and I'd venture to guess that's one of the reasons the 4e designers tried to move away from it.
Specifically, however - casualoblivion, did this player's style significantly hurt everyone else's enjoyment? I'm not sure if you've stated directly.
That's water under the bridge at this point of course since now the dominating powergamer has become the sad loner in your 4e game. Are you trying to help him find a way back to fun, short of telling him to find another game with a system that supports his style?
You note that "he's one of the best players around when we aren't in a competitive or tactical situation." How so exactly, I wonder? Good roleplaying, or what? Maybe you can try to draw him back into the game by trying to take some of what hooks him outside of combat and tying it back in to combat. It's hard to offer a more concrete suggestion without knowing more specifics... but if he's into playing up the dark secrets of his warlock pact, maybe the fiendish whispers are telling him that if he can kill someone that was struck by the wizard's spell, great power will be his. Ok that sounds lame, but hopefully that gives the general idea.
The other thing, of course, is to go ahead and try to give him the spotlight in combat occasionally. Let him have a one-on-one duel within a combat - an artillery monster that is pinning down the party that only he can get to by teleporting, or something. Not in every combat of course, but here and there, really giving him the spotlight might help him get into things more.