Space Empires 4 is a modders dream come true.
A ton of the game internals and graphics for ships and races are exposed in text and BMP files. I had a lot of fun writing some component, ship and race viewer utilities in Python/HTML for the SE4 community. One of them (done with Raynor) even made it onto the SE4 Gold CD. Now THAT was just really unexpected and very cool.
The SE4 game itself could have been the absolute best of its genre if only the AI were a bit better. It's just way too passive and doesn't put up much of a tussle. That pretty much takes all the fun out of the game for me. Some of the game mods do make the AI more agressive, but there's only so much you can do with the AI in mods. I have some high hopes for SE5, which is currently in developement.
The Dominions 2 AI I find to be VERY aggressive. This, and the the overall depth of the tactical and strategic options in the game, makes up for a whole lot of other shortcomings in the AI department, IMO.
I'm still learning the game so the sense of AI ennui I've read about in the Posts here hasn't quite hit me yet. So far it's a whole lot of fun.
-CS