Fair enough. As I posted a few times upthread, I read "aboutness" as going to "topic" or "subject matter". And I don't think that the subject matter of a combat-heavy game must be combat. The subject matter of the X-Men isn't fisticuffs (although its a fisticuff-heavy comic/movie). The subject matter of the X-Men is liberation politics.IMO, when people talk about combat in the way they are in this thread they mean something along the lines of "using game mechanics to resolve outcomes of a physical confrontation". Roleplaying may or may not be a part of that. If a game is "about" combat, it's about those conflict resolution mechanics, implying that other forms of conflict resolution are de-emphasized.
XP in at least some versions of D&D isn't based on killing things and taking their stuff. In classic D&D, treasure can yield XP whether it comes from killing and looting or in some other way. In 4e, non-combat conflict, quests etc can all yield XP, and treasure need not come from looting. (3E Oriental Adventures also makes a similar point about treasure in that game.)GURPS can also quite easily do a fantasy setting, and the advancement mechanic isn't necessarily based on killing things and taking their stuff like D&D is.
AD&D had personality disadvantages for all PCs - namely, the alignment mechanics - and for some classes these are particularly onerous (paladins, rangers, monks, to a lesser extent clerics). Whether or not these promoted roleplaying I think depended a lot on the group.GURPS has all sorts of rules interfaces that promote roleplaying through its disadvantages.
To me, this shows how differently various players and gaming groups think of roleplaying.WoD, both old and new, is all about roleplaying. I recall, during my group's experimentation with it, that in a published adventure it mentioned that you should punish your players heavily for attacking someone who is an "end boss" for the module, because "This is not The Legend of Zelda."
I'm not sure what sort of "punishment" the author(s) of that WoD adventure had in mind, but personally I regard strong GM force of the sort that White Wolf and 2nd ed AD&D tend to encourage as the enemy of the sort of roleplaying I enjoy, because it tends to block and discourage, rather than to cultivate and reward, players advocating for their PCs.
For similar reasons I'm personally not a big fan of "hard" personality disadvantages of the GURPS/alignment variety. But I know others like them.
And I don't find that using the system is necessarily at odds with roleplaying. Like I posted upthread in my long reply to Hussar, I think it depends on whether using the system supports/expresses, or alternatively distracts from, a player's enagment with the situation via his/her PC.Virtually any rules-lite system (or at least liter than D&D) is probably better geared for roleplaying because any time you spend messing with game system rules of any type could be spent roleplaying instead.
Burning Wheel would be an obvious example of a very crunchy system that is intended to produce roleplaying by using the system. Part of the system is "Say yes or roll the dice". The flip side of that slogan is that, where the GM doesn't want just to "say yes", the dice have to be rolled - ie a challenge has to be framed in mechanical terms, and the action resolution mechancis then used to address it.
My view, as expressed in my reply to Hussar above, is that if the players don't want to play their PCs, no amount of mechanical bells and whistles will change that (given that playing a game is a fundamentally non-coercive activity). Conversely, if the players want to play their PCs, then bells and whistles aren't essential, provided that the action resolution mechanics of the game don't actively impede the players playing their PCs.D&D, as written, doesn't really give a damn about roleplaying. You can do it or not as far as it's concerned, but there's not much of anything there in the way that the game is played that even encourages you towards it, even when it's not required. So to say it's about roleplaying seems pretty impossible to me. It's something you can do with it, but that's not the way it's written. GURPS has rules that come close to flat-out requiring roleplaying if you take certain disadvantages. WoD highly encourages it.
So whether or not there is anything in the way that D&D is played that encourages roleplaying in my view turns to a significant extent on how a particular group plays the game. (For my approach, see my reply to MarkCMG above, post #262.)