Have just got into an excellent free 3D Space sim abondonware game call Allegiance.
I could describe the game but the website I downloaded it from does it better:
Allegiance is a team-oriented space combat simulation that belongs to the massively multiplayer online game genre. This means that you primarily play Allegiance online with several other players, and that there is a very limited number of computer-controlled players on your team. Allegiance is unique in that each team has a Commander, which adds a more-than-complete Real Time Strategy (RTS) aspect to the game. The Commander is the one who should receive the team's money, manage miners and constructors, choose technology, invest money, and organize the team. All in all, he's the boss, and you report to him.
You are expected to obey the commanders orders in game. This is a team oriented game. Teamwork is crucial. One person wandering around aimlessly doing what they want hurts the team! You can expect to be removed from the game by the commander. Pay attention to the chat, do as you are told by the commander. If not sure what to do, ask!
There is no greater feeling than winning a game because your team worked together towards a common goal!
Another particularity of Allegiance is the quantity of players that can play a single game. Hundreds of players can participate in single game. Since Allegiance can support up to six teams on incredibly huge maps, these games don't feel even slightly crowded. The number of players involved in a game can have dramatic effects on what type of strategy is going to be used. A small game will be played on a small map, without too many resources, with small assaults played out between opposing teams. Large six-team games may involve secret alliances between factions, assaults using fleets of capital ships, multiple surprise/stealth assaults, teleport assaults, huge battles, sector overloads, and a lot more resources.
Strategic Basics
What draws players to Allegiance is the rich interplay between teammates and commanders, as well as the unlimited number of viable strategies that can be used to win a game. The choices in factions, ships, weapons, missiles and equipment create billions of possibilities, making variety a central aspect in Allegiance. There are hundreds of ways of doing the same thing, and there are hundreds of things to do.
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This is a very complex game with a very steep learning curve. I am enjoying playing it alot. It is very satisfying when you take part in a co-ordinated bomber run on an enemy base or win your first dog fight. It uses a semi newtonian model so piloting insnt easy, and to get the jump on the opfor you have to manage your radar sig so you can approach and ambush. It also has a very firendly mature community that is very friendly to the Noob as they all apreciate how long it takes to master the game.
I would def reccommend giving it a look, if you do look out for aceofspace which is my sig.
allegiance download