AI War:Map Size
Like many other RTS games, the size of the map has more implications than game duration, such as available Knowledge, AI Progress required to form a contiguous empire, and distance between objectives and rewards like ARS and CSG. The flow and style of the game can be pretty different depending on that parameter. Here is a general guide to what can be expected at each map size range.
These maps are fast and furious. There is very little knowledge to be had, so players will get very little technology unlocked. The AI Home planets are also extremely close by. Since players are unlikely to have very good tech, this can be an exceedingly hard map to play on. AI Alert Level is also much more challenging.
On the flip side, the AI Progress won't have a chance to go up much at all, and all of the Advanced Research Stations will be close by, so players will usually be able to mount pretty sizeable fleets, even if they are largely low-level. This is a completely different sort of game from the larger maps, though.
These maps are also very fast, but not quite so brutal as the 10 planet maps. There is a lot more opportunity for knowledge gathering, so players can mount a much more normal size of fleet and get a lot more of the technologies. This is still not as strategic of a game as the larger maps, but it's basically a "more techs, somewhat longer" version of the fast and furious 10 planet maps.
These maps seem to be preferred by a lot of new players, because they offer a pretty good amount of strategic depth while also being shorter than the 80 planet (default) map size. 40 planet maps are commonly taking as little as 7 hours to complete. With these maps players have plenty of knowledge, and lots of room to expand, but the rewards and goals are closer at hand than in the larger maps.
This makes it so that it is easier to "go for the throat" and win by skipping large parts of the map, and it also makes it so that the rewards can be a lot easier to obtain than in larger maps. In general this reduces strategic options some, but not terribly, and provides a shorter game.
This map size is the definitive AI War experience. However, anything smaller than this will have a bit less grand strategy than the game was designed to have, simply because things are too close together and players have to take fewer planets (and thus can have lower AI Progress) than they otherwise should.
Some new players are put off by the overwhelming size of these maps, or the extended amount of time they take to play (12-15 hours is not uncommon for these maps), but once more into the game, it is a better experience playing on maps of at least this size.
These map sizes are for players who like an even longer game. Everything is further away and harder to get to, and the AI Progress has an even better chance of getting higher. These maps tend to be harder, and take a lot more careful planning to pull off effectively.
These are the epic map sizes. Everything is very far away, very hard to get to, and players have a huge amount of frontier to protect. Just deciding where to go and what to capture is a huge challenge, and these games are often a very extended battle to the death between incredible AI hordes and the growing player forces.
The original version of the game shipped with 80 planets as the minimum galaxy size, but due to player suggestions the minimum was lowered to provide opportunities for other forms of play.