Purchase licensed version of the game Titan Quest. To play on the Internet, you need a official jewel-box: security system will not let you on the server without a registration key.
Play through the local network. Fortunately, the game on lan does not require the immediate availability of copies of the game, so play on connected computers can freely pass through the corresponding item in the main menu. In addition, there are programs like Hamachithat allow you to create the appearance of a local network when playing over the Internet. It works as follows: you install Hamachi itself and friend, create a common network. Then go to Titan Quest, select the menu item "play on Lan", then click the option "connect to IP" and enter the address of the second player. On the software screen will show "virtual IP" of your companion. Similarly, you can create a party size up to six people (internal limitation of the game).
Turn on Amateur forums. There you will find many fans of the game who will gladly accompany you when passing. For example, you can find ' constantly active servers on Hamachi.
Play as a team. When it comes to directly the gameplay, Titan Quest priority is a team game. Try to define clearly the responsibilities and enjoy all the advantages of playing several people at once. For example, if the single player is any distance fighter, you need to take care about health (because in any case he is under attack), then in multiplayer you can not do if you have a second player, which will divert attention to himself.