I was preparing a character for an upcoming sci-fi campaign, and was considering a little brawling skill. The min-maxer in me said, “Forget that crap! Unless you go super-monk, there’s no such thing as unarmed combat, and certainly no such thing as nonlethal combat.” And sadly, that’s usually the case. You don’t get too many nice fists-only bar fights, people always whip out the high impact weapons.
Which is a shame. Star Trek, for example, was always all about the unarmed combat; easily the wide majority over phaser combat. And unarmed combat’s great for plots. People don’t get killed, so you get prisoners, further interaction, etc. In fact, in many a movie/TV plot, people have a knock-down-drag-out fistfight and even become friends over the course of it. Of course, in an RPG everyone assumes any combat will be to the brutal death, and thus moves to deal it out before they take it.
One fix to this is metagame. The GM can just make it clear what is a “friendly” combat and what isn’t. In a friendly combat, you understand that nonlethal is the way to go, consequences for losing will not be severe, and it may be an opportunity for role-playing and not pure tactical optimization. Alternately, you can set really strong and realistic reactions to violence in-game. If there’s a bar fight, those just punching get off; those who shivved someone go to jail.
I ran a long term high immersion D&D campaign and had to do that at its beginning. I clearly set out my vision for the game, but old habits die hard. Two of the characters start asking around in a bar for information; one guy tells them to slag off; next thing you know they chase him out into a field outside town and shoot him with a crossbow. Luckily he was still alive when the local sheriff showed up.
The sheriff collected everyone and heard them out. Entertainingly, the PCs’ story was, “We thought he had information and he talked back to us and ran off so we shot him!” “Is that the story you’re sticking with?” “Yeah, why?” One of the two saw how it was going and voluntarily paid a fine and did restitution. The other one stuck to his guns, though, and wanted a trial. You should have seen his face when the mayor sentenced him to three months hard labor in the mines. Time for a new character! It sucked, but it made the point and people considered the consequences before they drew steel thereafter.