Rules:
- History of the world before your birth remains the same; only events happing after your birth can be changed.
- The other version of you must still be alive, you cannot go to a world that you are dead in. (This essentially forces you to murder/abduct your alt-self, so travelling has a ethical cost to it 😉)
- There may be other multiverse travellers out there
(Btw, is it ethical to murder an alternate version of your self? Is that even murder or just self-harm technically?)
Wouldn’t that mean you could never return to your home universe because a living version of you would be absent?
Yes, precisely. This makes the multiverse travelling aspect even more exciting.
(I mean, unless there was somehow already an alt-you from another universe that secrely sneaked in to your original universe before you left, then in that case, you could return.)
There just need to be a version of you in the universe as an entry requirement, not necessisarily the original version.