On Roleplay MTA servers there are predefined roles players can chose from. Some servers allow players to pick any role the want whole others require application for some roles.
Different Roleplay MTA servers?
Roles on Roleplay MTA servers can vary, but they're usually based on MTA server theme, for example you can't expect to find aliens on Cops and Robbers servers or maybe you can, it really depends on each RP server.
