[QUESTION] How to put special characters in your name?

It is only player_name if I am not wrong.

If your using mac from, what I've experimented with you just type

ALT (Option) and than a letter.

Some symbols are not supported, but you can try to use symbols writable with shortcuts on keyboard:
[ (Alt+F), ] (Alt+G), { } (Alt + B, N), @ (Alt + V), € (Alt+E), \ (Alt+Q), | (Alt+W)....

It is no deep secret how to make special characters and there are millions of sites who explain this in great detail. Anyone who wants to abuse special characters to fake a name would already have learned how to do this by any of these many sources. The "danger" certainly doesn't weigh heavy enough to keep this info away from the community.

As unfortunate as the practice of name faking is, the best solution against it is to make your team know all of it's members, both outside and inside the game. Then you'll know of each other who is who and have no problem to pick out any fakers that might be around. Another possibility would be to play on private (passworded) servers so nobody can interrupt your gameplay. Outside that this is one sort of trouble that will always be around in one way or another (or at least till there gets something like an account system).