Download this pack to get a host of new characters for Multiplayer (AUTOBOT HOUND, KICKBACK, SHARPSHOT and HARDSHELL). In addition you also get the Generation 2 BRUTICUS colors and 2 unique weapons for use in the single player Campaign (Retro Blaster and Shock Cannon).

Go to: http://store.steampowered.com/ and download STEAM client Click "Install Steam" (from the upper right corner) Install and start application, login with your Account name and Password (create one if you don't have). Please follow these instructions to activate a new retail purchase on Steam: Launch Steam and log into your Steam account. Click the Games Menu. Choose Activate a Product on Steam... Follow the onscreen instructions to complete the process. After successful code verification go to the "MY GAMES" tab and start downloading.