Your example is fun play. I like it, and I enjoy when such things happen in my game. What I don't see, though, is how your example illuminates the discussion about choice not being a challenge or risk to characterization. You player decided that this crisis happened, and, absent a scene or scenes where this crisis is tested in a way that the player risks their characterization, it remains just a choice the player made about their character.
I can see why you say this. But for me, this brings us back to [MENTION=16586]Campbell[/MENTION]'s remarks:
Players should play their characters with integrity and want to find out who they really are. They shouldn't try to drive play to some preferred outcome.
The absence of choice in the example I provided occurred at the point of the killing. At that point, thie player learns - without having any say over it - that his PC is a killer. At that point, playing the character with integrity generates the crisis. There were subsequent events, too, that played on the crisis. That's part of the GM's job (in my view) - once the pressure point is clear, the GM needs to work it, not relax it, so that the player isn't spared the consequence of what has happened. This isn't quite
GM decides, but it's a definite demand on the GM that puts the GM in a very different role from (say) the impartial GMing of Gygaxian D&D, or the most common approach to Classic Traveller.
The example of play invovling Nighcrawler that I posted upthread is somewhat similar in these respects. Events unfold which are not fully under the player's control (due to the use of action resolution mechanics). And as a result, the player, playing the character with integrity, finds that the character is changed. (In that case, Nightcrawler discovers that he is not as romantic and perhaps not as devout as everyone, including the player, thought.)
I appreciate that this does not unfold the same way - in terms of the interplay of choice and mechanics - as what you've had in mind in your posts. I think it's also very different from the example of choosing chastity or Excalibur. In that example - as it has been presented - there is no moment of crisis. There is nothing that has happened to the character that forces a reconsideration of who s/he is.
Here is also another angle on it. As presented, the Excalibur choice can come down to mere expedience - and has been framed as that by some posters: is the short-term gain of the Excalibur power-up worth the long-term loss of (say) fellowship with members of the knightly order, or the king's respect, or whatever else is forfeited along with the chastity.
Whereas in the sorts of examples I am putting forward, expedience is not a consideration. The player is forced to choose a way forward for the character, and is not guaranteed to be able to succeed in the way chosen.
I'm not familiar enough with RM to say either way.
RM is in many ways a D&D variant. But it has a few points that differentiate it from straightforward D&D of the era. The possibility of non-fatal victory in combat is one; aspirations towards a non-combat resolution system is another. The latter rests on a skill system which has - as a side-effect - the generation of PCs who are far richer in detail and hence implicit characterisation than an AD&D PC.
There are also some features of the actual resolution system which - while there is nothing like "fate points" - allows a player to decide in what sorts of ways his/her PC tries hard to succeed and what risks s/he takes, both when fighting and when casting spells.
So while it's easy to bundle RM into the pile of late-70s/early-80s ultra-sim games, it has these features that make it a distinctive vehicle for character-oriented RPGing.
When I look at a system like Burning Wheel, it has a lot of tech that RM doesn't: a system for metagame currency (Beliefs, and the fate points etc that are related to them); much much better action resolution (intent and task, let it ride, "fail forward"); and PC development that is much more tightly integrated with player choices. But the basic devices for putting pressure on the character, and driving change, are the same as what I've described in my examples of play.