FreeGameDev

Hey, I'm very new to STK and I have looked, but I cannot find any option to use arena maps/use the 3-strike battle gametype anywhere in my game.

Sorry for the newbie question, thanks in advance.

The 3-strike battle is multiplayer only, because there is no AI for this gametype.
You have to start a multiplayer game in order to see the 3-strikes gametype.