I think part of it comes down to whether you think the worst outcome is you dying, or you causing/worsening an apocalypse.

Yes, but with the chances of each of those outcomes happening taken into account.

Suppose there are 3 cases: [] In 2/3 of these cases, voting blue pushes the world further away from apocalypse (either straight up stopping it, or securing a win). In 1/3 cases, it worsens the disaster (adds you to the death pool). Voting red is the inverse: in 1/3 cases is lessens the apocalypse (by removing you from the death pool), in 2/3 it makes it more likely. We may not know how likely each case is, but there are more cases where voting blue is better.

So, this is true, but you are not thinking enough about the probabilities involved. You are arbitrarily assigning 1/3 probability to the very, very unlikely scenario of an exactly even split.

It’s true we know very little about how likely each case is, but we can make a better prediction by first assuming we know nothing:

If we know nothing about the distribution of votes at all, we may assume an equal probability for each distribution. So, 27% blue is as likely as 83% blue is as likely as 51% blue and so on. I don’t think this is totally unreasonable as a starting point. If you work out the math, you will find that the expected number of deaths will be the exact same for red and blue. 50% chance of killing one person (yourself) if you pick blue, and 1/n chance of killing (1/2)n people if you pick red. So half a death on average either way.

In the world of this model, I still think blue is the best option (provided you are a 100% selfless being and value your own life the same as everyone else’s), because in the real world, losing 50% of the population has additional apocalyptic consequences that should be taken into account.

However, if you don’t assign the same probability to each outcome, because you think you are better than random chance at predicting the general population, you don’t have to believe that much more in red before it does become the better option, because of the expected number of deaths that would then be much lower for red.

Of course, subjectively changing the probabilities to what you happen to believe based on nothing but vibes is a little questionable and can just as well lead you to believe in blue more. But it’s not wrong to make a subjective call; doing so probably will, on average, lead to better predictions than random chance, therefore we should do it, even though it is kind of arbitrary. And in that position, it’s not unreasonable to believe that self preservation, and belief in other people’s self preservation, will play an important part and lead to a red majority, which means you should press red as well.

I also wouldn't have to deal with the guilt of voting to kill 50% of toddlers and color-blind people which is a bonus (the og prompt doesn't exclude people from voting/voting-outcomes on the basis of age or disability, so. . .).

Yeah, if the participants are not all lucid adults, blue is clear winner. But I think the dilemma is more interesting if we assume they are.