But after rifling through a half dozen titles he's played recently--including Advance Wars, Mercenaries, and Halo--Sid Meier, legendary Firaxis designer, admitted that he has yet to play Valve's Portal.

"When [Civilization Revolution] is done. On my pile of games to play."

With the upcoming release of Civilization Revolution, much of the Game Developers Conference Q&A with Meier was unsurprisingly devoted to the addictive strategy series he is known for.

Speaking of his team's early days on the original Civ, it turns out that even Meier was shocked at how enticing a round of Civilization could be.

"I actually did not really expect the game to be as addictive as it was," said Meier. "Every game had its fans but this kind of universal addictiveness.. was scary."

Meier went on to admit that much of the winning Civilization design amounted to luck, attributing the rest to a guiding philosophy of fun.

"One of our kinda key roles in game design is 'who is having the fun?' It's important that the player has the fun in the game," he said, noting that there is a temptation for the designer to steer the gameplay too much. "It's definitely our philosophy to keep the game designer in the background and let the story emerge from players' decisions."

The Firaxis co-founder then touched on the burgeoning casual games market, arguing that the definition of "casual game" can vary.

"It's interesting. I think the word casual is kind of a tough on to pin down. I think there can be casual simple games. If casual is a measure of game cost, that's one thing," said Meier, who then noted that many of his games could be considered casual by that definition.

"Bring the players' imagination into it. That was something that was really different about our early games," he said, giving an example of 16-bit games that needed to rely on a player's imagination to work. "It's finding a way to trigger those responses. Imaginations are still around today."

When asked of Sid Meier's Dinosaurs, the short-lived dinosaur title in development at Firaxis circa 2000, Meier put the canned game in Starcraft: Ghost territory.

"Certainly not an idea I've given up on. Certainly might be an opportunity in the future to do it right."

"I like to spend time with an idea before I really let people know what I'm working on," he said, adding that the dinosaur project only wasted his time, and stressing the importance of identifying failures ahead of time.

Talk then shifted to the upcoming Civilization Revolution, which Meier referred to as a way "to approach the Civilization idea from scratch."

"It's a designers dream to repair the past or go back in time. This is kinda an opportunity for me the designer to go back in time with a lot more knowledge and experience."

"That has been a lot of fun, to kinda see the ideas I wanted to see in the original Civilization come to life. To put you back in the king spot. You're making the big important decisions. Everybody hangs on your every word. You are the king. You can pick your own strategy. There are different ways to win the game.

"Every decision is interesting. You really want to go back and create a new story.. to see what would happen if you'd gone in a different direction," he concluded. "The essence of Civilization."

But after all these years developing such expansive worlds, what motivates the creator of Civilizations to continue?

"To play a game that hasn't been written yet. To fill a void."