Symphony D.
Deity
If the number of times an agent can go back in time is unlimited and largely unbounded, no, they don't need to understand the new history—they're unlikely to ever even be in the same time as one another except right before trying to eliminate one another. It behooves all the players to constantly be mucking about with one another and/or time until they are finally in a position to kill another peer, not for any substantial number of them to exist in one time. In this way, it does become a singleplayer-focused multiplayer game, and you're having to deal with multiple, possibly contradictory times at once. Your players are far too scattered in time to meaningfully interact much.
So you have to largely lock them into one time, and you need to limit how much they can alter. This inherently suggests 1 or 3, leaning towards 3, due to hard limits on how often they go back per unit time. But even then you run into this narrative problem; Let's say it's Update 5. Player 1 goes back 4 updates, Player 2 goes back 3, Player 3 goes back 2... how does that all interact? Do you play it in "sequence"? Write Player 1's part of the update first, show it to Player 2, write his, show both to Player 3? You're again constrained by the fact not all of them are likely to be operating in the same time. (And if there are no paradoxes, then their actions don't matter, because they can't change the future (which is what causes the paradoxes); they're merely acting out doing something they've "always done." In which case what's the point of time-travelling anyway?)
I would say the entire idea of a time-travel game is kind of terrible and an administrative nightmare, but if you had to run it, I'd say there are two big options:
A. Some kind of time machine the players fight for access to, which only takes one back to alter the timeline (for some brief period of time, like a day); all the others that failed to access it get shunted into this new timeline and can again fight for access to this machine, to make their own alterations, repeat ad infinitum. This makes the new history "matter" vis-a-vis their survival, keeps them all in the same timeframe, and simplifies administration.
B. Whenever one of them goes back to a time, they all go back to that time (how you resolve who gets to choose is an open question) for some time period (again, say for a day) and get to alter things, before being sent back to when they "left" which has been altered by all their actions. This again makes the new history "matter," since they'll be in it at least some of the time, keeps them all in the same timeframe, and again simplifies administration.
So you have to largely lock them into one time, and you need to limit how much they can alter. This inherently suggests 1 or 3, leaning towards 3, due to hard limits on how often they go back per unit time. But even then you run into this narrative problem; Let's say it's Update 5. Player 1 goes back 4 updates, Player 2 goes back 3, Player 3 goes back 2... how does that all interact? Do you play it in "sequence"? Write Player 1's part of the update first, show it to Player 2, write his, show both to Player 3? You're again constrained by the fact not all of them are likely to be operating in the same time. (And if there are no paradoxes, then their actions don't matter, because they can't change the future (which is what causes the paradoxes); they're merely acting out doing something they've "always done." In which case what's the point of time-travelling anyway?)
I would say the entire idea of a time-travel game is kind of terrible and an administrative nightmare, but if you had to run it, I'd say there are two big options:
A. Some kind of time machine the players fight for access to, which only takes one back to alter the timeline (for some brief period of time, like a day); all the others that failed to access it get shunted into this new timeline and can again fight for access to this machine, to make their own alterations, repeat ad infinitum. This makes the new history "matter" vis-a-vis their survival, keeps them all in the same timeframe, and simplifies administration.
B. Whenever one of them goes back to a time, they all go back to that time (how you resolve who gets to choose is an open question) for some time period (again, say for a day) and get to alter things, before being sent back to when they "left" which has been altered by all their actions. This again makes the new history "matter," since they'll be in it at least some of the time, keeps them all in the same timeframe, and again simplifies administration.
Cant wait 
