[Maltrease]

Here is another idea. Although this would be much better for a MP game instead of AI.

A map like this (see attachement) could be built for any number of players. Basically a spoke wheel of sorts. Each player will have only have direct contact with 2 other player. You could have any number of provences between the players, and on the inner wheel. The center provence should be guarded by an insanely powerful group of Indies with commanders able to withstand most remote attack spells. Also load it up with powerful magic sites (50% off spell cost site). Make the 2-3 provences near the center also guarded by powerful indies in each spoke, to make it difficult for a flying race to hop over them.