Allegiance is an online multiplayer game (the only offline component is the tutorial) with action and strategy elements, comprising a fusion of real-time strategy and spaceflight combat simulation. Originally developed by Microsoft Research, the game was published for multiplayer play on Microsoft's Gaming Zone platform in 2000 under the name Allegiance Zone. The game was not commercially successfully, and its servers were shut down in 2002.
In its two years of operation, the game acquired a loyal and active player community who continued to play using player-made LAN servers and client software. In 2004, Microsoft released the game's source code under a Microsoft Shared Source license, and the community has since maintained the game under the name FreeAllegiance. In 2017, the community sought to bring the game to Steam, and Microsoft changed the license to an MIT license, and it is now freely playable on Steam as Microsoft Allegiance. The community continues to operate at the FreeAllegiance web site at www.freeallegiance.org.
Allegiance features six playing modes: (1) deathmatch, (2) deathmatch with a time restriction, (3) capture the flag, (4) prosperity (generating a certain income), (5) artifacts (searching for artifacts), and (6) conquest (conquering all systems). Up to 75 players can participate in a match, with 2-6 teams of 3-15 players each.
The game is played as a spaceflight sim from either a first- or third-person perspective, with an overhead perspective available. Players can take control of a variety of different space ships with different tactical uses, from regular combat and stealth fighters to capital ships and utility ships, such as salvation ships which can rescue downed player pilots and allow them to respawn immediately. Players can also serve as turret gunners on other players' ships.
On each team, one player serves as Commander and coordinates the team, explores unknown sectors, and sends out vehicles to exploit resources. Another player serves as Investor, administering the team's funds and using it to research, build production plants, and upgrade ships. If it is preferred, the Commander can fill both roles.
While Microsoft's Gaming Zone was originally a paid subscription service, players could play for free on the reduced-feature Free Zone. A paid subscription to MSN was necessary for statistics comparisons or registering squads (similar to guilds from online role playing games).