(This comment is a reply to another branch of this discussion as well.)

Yes, God will be able to see that there is a you that survived the process and went on to live the life of Riley. But whether or not you will be able to see that is a very open question

I disagree. To keep things simple, let's suppose that the bullet, if it hits, really will kill the participant with practically 100% certainty and will do so practically immediately (I'll come to this a bit later). In that case the only outcome the participant can expect to experience, and that they will experience with certainty, is that the gun didn't fire. This is exactly what happens if you take the mortal's-eye-view; God, as you mentioned, will notice that elsewhere in the multiverse, the participant did get hit. Now, whether the participant cares about their loved ones or the copies that die in the attempt is a matter of preferences, but if we're simply talking about which outcome to experience, this is how it goes, I think.

Note that playing quantum roulette successfully depends crucially on the speed with which you can kill yourself. Trying to play by slitting your wrists, for example, doesn't work because once you see that your wrists are slit you can't roll that back. So the success of the enterprise depends entirely on killing yourself fast enough that you don't become aware of your imminent and (in the relevant branches of the multiverse) unavoidable death. How fast is fast enough? Well, that is (literally!) the sixty-four-million-dollar question. Unless you have an answer that you are very confident is the correct one, it seems to me like an imprudent risk to take.

With this I agree, which is why I think the quantum Russian roulette or quantum suicide scenarios are mostly interesting as a thought experiment, as they're intended to be. But there are practical situations that are somewhat analogous: think, for example, about a terminally ill patient who faces an almost certain death within several days. Should they expect to survive or continue to experience things, and if so, in what way? My understanding is that according to quantum mechanics, there are all kinds of weird scenarios with non-zero probability that make "survival" possible, such as simply surviving one more day indefinitely despite all odds, being miraculously cured, or maybe being resurrected by a hyper-advanced future civilization in a simulation. Note that, in principle, this probably applies to any possible life-and-death situation.

I used the word "experience" a number of times there, which brings me to a point you made in another comment:

Notice (!) that when you start to talk about "noticing" things you are tacitly bringing consciousness into the discussion, which is a whole 'nuther can o' philosophical worms.

I don't think this can of worms is that bad. We have a pretty good grasp of what it means to be conscious, even if we can't define it exactly; and also we're (at least I am) pretty confident that it's a purely physical phenomenon with nothing supernatural and thus subject to the laws of QM. I think that's enough. Where it does get a bit problematic is when we're talking about scenarios like the one with the terminally ill patient; presumably there's also a possibility that the patient's consciousness degrades until it no longer makes sense to call them conscious, since there's probably no clear line anywhere separating conscious and non-conscious in this way. (This might also imply that if we should expect to die, we should expect to do so by very slow decay, like patients with Alzheimer's, which doesn't sound too good to me.)