One of the few Sci-Fi concepts that hasn't turned up in 4X games has been Time Travel - obviously because the mechanics of it would be an absolute nightmare in games with a linearr progression. Full on time travel would of course be incredibly difficult to implement - requiring data from the entire game and constant chopping and changing.

What I'd like to propose is a 'lite' time travel idea that would make use of an autosave function. Essentially how it would work is this: when getting to the top of the tech tree the player can install an experimental 'Time Drive' on to one ship. If the player chooses to activate this drive they pick one of the old autosaves.

The game as it stands is then closed, with the old autosave loaded instead, with two differences: One, the ship with the timedrive is inserted, and two, the player recieves everything on the tech tree they had in the 'future'. They can then, thanks to superior technology and a ship from the future, proceed to kick ass and conquer the Galaxy.

The main stumbling blocks with this would of course be that
1. it wouldn't be workable in a multiplayer game, since other players would be forced to lose their progress when they wouldn't want to.
2. How to handle the possibility of AI races getting the device.

1. Isn't such an issue if (such as Galciv) the game is not multiplayer but 2. would present difficulties. A possible solution might be to provide for a massivley unlikely random event during a game in which a timeship & techs are spawned for an opponent, but it would still be troublesome and unfair to say the least.

In practice the actual time travel would probably have to be only available for a single human player.

It could be integrated into the tech race - so rather than chasing Transcendence or a ship to Alpha Centauri the player is racing the other races to Time Travel - if you're beaten then you lose the game, if you win you then get to do the rewriting of History yourself if you want.