tl;dr — Epic in every dimension. And, despite all the ISC brouhaha, it plays just fine right out of the box.
UPDATE: This is still a great game, the experience growing more rich and nuanced as we become more familiar with it. This is definitely one of those games that requires repeat plays—difficult for most, I know, as the first couple of plays can be excruciatingly long and fraught with error. All I can say is stick with it; like the monster games of old the wonders in this box are only revealed through familiarity.
ISC and other tweaking:
The best version of this game is played with the Age of Empire & The Ancient Throne variants. AoE, found in the rulebook, lays all the public objectives out in a row and allows for long-range strategic planning. AT, an official variant found on Fantasy Flight's website, changes the ISC to 1VP if you control Mecatol Rex—in addition, it allows you to earn as many VP objectives as you qualify for, all at once.* It makes for a longer game (with no 2VP clock counting it down) but with far more interaction, with emphasis on the ACTION!!!
*This is also now the Imperial II Strategy Card found in Shattered Empire.
Board setup for more interaction:
Take the best double systems and place them randomly around Mecatol Rex (so the first ring is made up of resource- and influence-rich gems of the Empire). Then build the other rings as normal. This prevents the usual layout of the galaxy—with players each residing in their own premium "turtle pockets" that are bordered with crap while the throneworld of Mecatol Rex languishes in a backwater ghetto. Surrounding it with double systems forces players to move fleets up the ladder and into sweaty proximity around Mecatol Rex for a turn (or so) of hard stares and eye-twitching until someone pulls the trigger on the Last War and makes the jump for Mecatol. With everyone having a fleet one hex out, the game becomes a Rolling Storm of Woe mitigated only by political shenannigans and shady trading...
UP-UPDATE: Aw, hell... who am I kidding? With the advent of the Shattered Empire expansion, this is a rock-solid 5-star game. Slathered miles-deep in theme, diplomacy & intrigue, massive space fleet engagements & ground combat—there's nothing else like it. Nothing even comes close.
This is simply put one of our era's finest games. Broad in scope, ambitious in execution, this is a game all ATers owe themselves to try.
If War of the Ring, Game of Thrones, and Doom were the opening salvos, this is the game that put FFG on the map to stay.
The threaded actions and role selections do crib from Euros, but it's a welcome evolution as classic but sometimes stodgy AT designs got a boost in the arm from some of the better ideas to spring from the Eurogame revolution.
If you are an AT fan and opening this box doesn't give send you into plastic-induced ecstacy, you are dead inside.
This one's got it all...combat, negotiation, secret objectives, wildly unbalancing action cards, variable player powers and races, a political system...
Try it now. This will be one of those games that will be sought after years from now.
I write this assuming you have the shattered empires expansion. You need this to make a good game great. That being said.....
Twilight Imperium is the best 4x game available as of writing this (2008). Accept no substitute this game has it all and it does it all very well. This is the type of game folks will be paying big bucks for years from now when it is out of print.
ti3 plays well from 3 players up to 8, with the major difference being game length (1 hr per player + 30 min for folks with less than 3 plays). I personally like 3, 4 and 6 player games the best in that I feel they have enough inter-player combat and still move along with little down time. 8 player games are fun but usually require a day to be dedicated to the game.
Aspect of this game I really enjoy.
Uneven Racial Benefits. There are plenty (14) of races available with ti3 and each plays slightly differently. Some are easier than others, but the meta game usualy helps balance this out.
Multiple Paths to victory.
The VP system really drives the game here. Many of the original VP objectives were lacing in that they did not encourage space combat, this was fixed with Shattered Empires and with the addition of Artifacts game play is opened up a lot. I have seen games end suddenly by an aggressive player scoring a 2 pt objective, their secret objective and taking an artifact planet via combat.
Most of the time we play this for one reason, to build a bad ass fleet of kick ass ships. The tech advances in this game can really make a difference. All about combat.. go red. Want a strong economy focus on yellow, mobility Blue, elite ground units are all about green. Focus, or go for a balanced approach. The late game abilities of different races are wildly different than those at the start of the game.
Arguably the weakest aspect of Ti3, but possibly most overlooked. A strong political card played at the right time can win or prevent another player from winning. It is hard to do, and that is why I think most people feel it is weak, but it can be done and the ability to pull off a strong political play separates the men from the boys.
So if you like big, all encompassing games, one you will think about for weeks after playing trying to figure out how Malloc kicked you ass on turn 5, then ti3 is for you. I cannot recommend this game enough.
This is exactly what I wanted when I got into this hobby. Each game has told a different story. Very cinematic. There's such incredible variety (especially with the expansion) that I doubt my enthusiasm for it will ever wane.
Long game, though it doesn't feel like it because I'm invested in it for its duration. Still, it probably won't be played as often as I'd like because of the length. Having said that, I'll probably still want to play it 20 years from now, so I'm sure I'll get my money's worth and more over the years.
It can be easy to get lost in the details and miss some minor actions, but that seems to be less of a problem the more I play it.
Also, the victory conditions are relatively weak in terms of theme.
I've been playing this game since first edition and it has been a joy to watch it evolve and mature into what i consider the current pinnacle of board games. With the addition of the shattered empire expansion this game became top dog in my books, the depth of strategy and game play variance as well as the length of the game(long is not bad) make for the most epic experience you can have with a board game.