At the start of the game, you can choose among several different races, each with special attributes. This makes repeated play interesting, even after you've won on the hardest level.

Orion's galaxy model is two-dimensional and static. Each star system is represented as a single planet, and is managed as a single entity. There are five types of planets: terran, jungle, desert, barren, and irradiated. The latter two require certain technological developments for colonization.

Planet management involves setting relative investment in five areas: research, industry, environment, ship building, and planetary defenses. Maintaining these settings properly becomes a huge burden towards the latter part of the game, when you may have close to a hundred planets. Still, you feel obliged to do this, because the computer does such a lousy job on its own.

Orion has a very flexible ship design module that's tied to technological advances. Existing technologies are miniaturized as new technologies are developed. Technologies are developed in realms, without any (noticeable) interplay between these realms (no technology "web"). Once you've incorporated your latest technologies into some ships, you can send those ships into battle, but the ensuing combat is terribly iconic, and really only serves to indicate a winner.

Orion has some diplomacy features, but my extensive play has revealed that diplomacy is more a waste of time than anything else. (Later versions of the game have reportedly fixed this problem, such that there is some benefit to be gained via diplomacy.) Spying is modeled in an interesting manner, such that investments in spying and counter-intelligence have long-term effects on the outcome of spying endeavors. Spy "incidents" can have significant diplomatic repercussions, so some attention and resources must be devoted to counterintelligence.

All-in-all, Orion is a huge improvement over Civilization, and has provided me with months -- even years -- of entertainment.