Master of Orion 3 is a game made by Infogrames Interactive that is your typical sci-fi game fare. You pick from one of 16 species, and you start your space empire.
The basic concept here is that you are one of the many races in the galaxy, and you have to rule all the other races, by force or otherwise. Of course, there are some wrenches in the works; the all-powerful New Orions (The Antarians from MOO2), the Antarian Xs, the Orion Senate, and of course random events. Not to forget the other races, some of whom are extremely powerful.
The Orion Senate is mentioned briefly in the above write-up, and I'll go into detail a bit more here. The Senate is a group of races picked randomly at the beginning of the game. Any race in the Senate can motion one of a variety of things, and, if seconded, will be voted upon to enact the rule (or whatever) in all of the planets of each race in the council. Keep in mind that each race has a number of votes equal to it's population points, while the New Orions have a number of votes equal to their population points, as well as a 1,000 vote bonus for starting the council. The motions are what you would expect from a MOO game, things like war and treaties and the like. For example, if you really hate the Trilarians and not only do you want to kill them, you want everyone else to kill them as well, you could motion for Total War against the Trilarians, and if it is seconded and passes, all the races in the Senate would declare Total war against the Trilarians. As well, these things could happen even with you off the Senate, so irritating several Senate members could be a bad thing.
Moving on to victory conditions here, there are three: Conquest, Senate, and Antarian X. Conquest kind of speaks for itself, but the others don't. You get a Senate victory if you manage to be elected as the head of the Orion Senate and elections happen every 20 turns or so. Because of the 1,000 vote bonus the New Orions have, this is really hard to do until further into the game. This victory condition is basicly the same as the Council victory in MOO2. Antarian X is the only really new one, where you find the five Antarian 'X's, lost pieces of old Antarian technology scattered about the galaxy. Each one contains a new technology that is only available with the X.
On a bit of a tangent here, I'd like to point out that the new system of movement in this game (Star Lanes connect stars together, and movement between stars without Lanes is abysmaly slow) is completely ripped off off Ascendancy. ...Not that that's a bad thing, it's a good system.
The races are:
Humans
Psilon
Evon
Imsaeis
Eoladi
Silicoids
Meklar
Cynoid
Trilarian
Nommo
Ithkul
Klackons
Tachidi
Sakkra
Raas
Grendarl
writeup to be edited as I make way in the game