Stars!

The Good
This game is so well balanced it is a piece of mathematical artwork. It allows a huge number of people to play (26) over the web, or a hot seat LAN. It is extremely easy to host online or by e-mail. The development and use of technologies in different paths is outstanding, allowing for vast minefields, bombardment with giant asteroids, economic strip-mining of planets, sneak attacks unseen by enemy sensors, improvement of your colonies from bare survival to prosperity and surprise battle outcomes when your most clever designs succeed or fail against the best of the enemy. Race design is intricate, and you can create races that breed like roaches, or ones that can survive on desolate Pluto or Mercury type worlds.

The Bad
It would be cool to be able to manage your battles hands-on, but then that would not be compatible with PBEM where there can easily be 100 battles per turn on as many star systems. So I guess it is a moot point. Sure wish they were still in business, and that Stars! Super Nova had made it to market.... sigh.

The Bottom Line
Hands down, the very best 4X game ever created.... start with 1 world, move on out exploring, create your own race, advance your tech in very tangible ways that improve your in-game abilities, and try to beat one of the most ruthless, non-cheating AI systems you'll ever encounter. This was the logical descendant of the old Reach For The Stars from the 1980's..... and what the remake of that game should have been. Since then no other game has shown nearly the same flexibility or mathematical beauty inherent. No other game I've ever seen is compatible with a spreadsheet use to calculate your moves. Its a game that would appeal to statisticians, accountants, and other math-minded people.