Hi everyone!
Right now i am making a 3d, 3rd person horror game and what i want to accomplish is, when the player
moves outside of the map (plane) it should return on the other side - like in pacman.
Anyone got any idea how to do this or can direct me to a tutorial or earlier post? Any help
is appreciated! 
I guess it would depend on what type of player control method you are using and what type of effect you want. Pac Man just runs (chomps?) off screen, then basically teleports to the other side, which can be done by setting a new transform position.
If you game map (plane) is centered at origin (0,0,0) and rectangular or square then I believe all you need to do is multiply the direction of movement by -1. If it is odd shaped you may need to use a little bit of logic to set the new coordinates.