GMod Tower was a unique community-based lobby with centralized multiplayer games. It was a modification within Valve's Source Engine. GMod Tower was a collection of various online multiplayer games that each have different genres of gameplay. Each game could be played with 4-90 players across the globe and are complete modifications of the Source engine. The lobby aspect is what made it all work. Players connected to a central lobby server and group up with other players to play these multiplayer games. While in the lobby, they could also watch Youtube together, buy furniture and items (such as a piano) for their in-game house, customize their look (hats, skins, etc), bet on casino and cards games, play trivia and arcade games, and participate and various daily activities.