Variables

Are Variables shared among all computers in a game or are they
kind of local?

That means, if I set a Trigger to modify a variable on one Computer
( say, by putting a condition for the trigger that it only runs
when player == local player )
would the variable be different on all other computers,
or only on the one the actually did run the trigger?

What it prolly would do is cause a server split or crash the game.

You can actually make local variables. But setting a Global variable as a Local would probably do as said above...

However, trough JASS (I don't know how, it was a long time ago I read it) you can make local variables for all players.

Regards
Dead-Inside