To play Tactics Arena Online (TAO), you'll need to create a free account. Visit TacticsArena.com (Commercial Version) and click "Play Online" or Play for free also at Developers Version. When the game has loaded, choose a server: Great Lakes, Banff, or Armageddon (Unique server at Developers version) and enter your desired username and password. Click the New Account button and retype your password.
Once you are logged in, you will see the lobby. The lobby has nine floors, each of which can host up to 20 battles. Click an empty square on the floor, and soon another player will join you in battle.
TAO is similar in nature to chess.