As a continuation of my No One True Game, train-wreck-of-thought, consider Mephit James' gaming blog and their recent roundtable post about what game engine would you use when playing in the Civilization: Beyond Earth video game setting.
What I find particularly interesting is that this isn't just the author's take on what they'd do but has the disparate input of several fellow GM's and their take on how they'd run their own games in a common setting.
The discussion exemplifies that there's no such thing as one universal system and that the choice of game engine really depends on what you want to emphasize and embody when telling your stories. The GM's that contributed identified such game systems as Infinity, Uncharted Worlds (an Apocalypse World variant), Coriolis, Mutant Year Zero, and one of my personal favorites: Eclipse Phase. Each of these games has a different focus, different emphasis, and different 'character' and therefore color how your experience playing that setting with those rules would be.
It's rather like asking: "What would a Harry Potter-verse movie be like if directed by Ron Howard? Or Michael_Bay?
Or Uwe Boll?"
(but seriously: don't consider the latter two)
Such discussions expose lesser known game systems to a wider audience (I now need to check out Uncharted Worlds, and its many supplements, for example). This can only be a good thing in the long run, even if it introduces some short-term hits to the wallet and adds to the what-do-i-run-next windmill of thought.
In nearly all cases the GM's also talked about how they'd tweak, modify or otherwise adapt those engines to suit the setting. That's another important takeaway from this discussion: Its okay to hack your core rules to align closer to your setting goals.
Lets shout that out again for the lizard brain: It's okay to hack core rules when a tweak or two will make them even more suitable to a different setting.
The Apocalypse World Engine is a great example of this kind of fan-made alteration. I've seen offshoots focusing on MechWarrior-style mercenary campaigns to crash-landed-aliens-trying-to-adapt-to-modern-human-culture (think an anime version of Alien Nation).
