Aces High (formerly known as Aces High II) is a combat flight simulator and massively multiplayer online game for Microsoft Windows. It was created by HiTech Creations and originally released on May 8, 2000, the game is subscriber based and is constantly updated and upgraded. It features aircraft from both the World War II and World War I eras, as well as smaller numbers of ground vehicles and ships.
While the main focus of Aces High is on World War II aerial combat, there is also a smaller selection of ground vehicles, ships and World War I aircraft. There are over 100 aircraft, vehicles and boats individually modeled in the game.
Source: Wikipedia, "Aces High (video game)", available under the CC-BY-SA License.