World Wynn In The Future

Or maybe, you can travel a multiverse with someone, where things are infinitely possible, like travelling into a dimension where Humans lost.
and then it could be like a full access area by going into a ??? style lab (no puzzles involved lol).

 

Well, it might be you being shown and helping out the survivors there but ultimately having to change some catalytic even that triggers that future. Perhaps with advice or a weapon from the future? Then obviously time shatters from the paradox effect and you move through a void like area to tie it all back together at the doors of time, fighting off extra-dimensional creatures or something. Maybe with the help of the Ancients (For tying the Timeline of your world back together). All in all, it could apply a much deeper meaning to the valley of time which always seemed very cool yet really useless and underdeveloped. But that's my personal take.

 

Time travel as a large part of the plot isn't a good thing. However, getting a glimpse of an apocalyptic world, then trying to save it, is fine. Still rather cliche and not the best, but far better.