Guns of Icarus Online is a steampunk/dieselpunk, multiplayer, first-person shooter that focuses on airship combat. Each airship is controlled by up to four players, with each member of the crew taking a specific role. Players can choose three different classes: gunner, engineer or pilot, which will allow them access to different kinds of tools. The commander of each ship chooses which weapons to use in his/her ship. There are also several ships available.
Source: Wikipedia, "Guns of Icarus Online", available under the CC-BY-SA License.