I just wanted to mention something I came up with for my game world:

Within it, people believe in a 5-dimensional world. Or, as they'd say, there are five directions, three of wich can be walked either way, and two that can only be walked one way.

The first three are spatial (up/down, forward/backward, left/right), the latter two are temporal (earlier, later).

So past and future are independent dimensions, rather than forward and backward on the same axis.

This effectively removes all kind of time travel paradoxa - if you first "travel" one minute into the future, and than one minute into the past, you do not end where (or rather "when") you started, but sqrt(2) minutes away from it (by the theorem of Pythagoras).

There is no such idea as to "turn back time" - time only turns forward, either into the past or into the future.

This might be hard to imagine for someone used to think of time as *one* axis, but someone used to think of it as two axes and never coming up with the idea of one axis could live consistently in this worldview, at least in a fantays word. And he would in turn find theidea of one axis rather strange.

And to be honest...I'm not even sure if modern real-world science could easily prove the idea of two time axes wrong (there even might already be such a theory of two axes, but if so I do not remember it).