Free Roaming War-torn Countries
Only the Mercenaries series and the new Farcry game has done this. Come on people, I want to explore the area not go down some set path through the river and over the woods to grandma's house. I don't MGS4, because despite the size of the map, you can't explore it that well.
Any Historical Background Other Than WWII
These games are definitely non-mainstream because now e have to actually read to find out what's going, Oh no! Holy Marketing Disaster In Action, Batman!
The Subway
We always go with the sewer and the train, but what if you mixed the two, you get a damn exciting sequence that's what, its too bad most games mess up subway scenes, to be even cooler, you could play Riding On The Metro by Berlin in the background.
Cities Outside The US
Where's Grand Theft Paris or Sicily? I'd rather be jacking cars in a foreign land than be subjected to the same crap again and again. We'd like to be killing random
Frenchmen in front of the Eiffel Tower, I'd even take Grand Theft Moscow, if it meant something new to the world of sandbox, well, hey, we could go with the middle east, see, there's a world of possibilities.
Inside People's Minds
Only Psychonauts was this bold, to totally flip the mind-reading process on its head, just play and you'll see what I'm talking about. Most of the time, we were inside the world of dreams in trippy sequences that were essential small breaks between the action, Psychonauts made that the entire game and then some.
Airport Levels
This is a direct result of 9/11 PC BS. Who doesn't want to shoot up the same perverts who think grabbing asses and patting crotches saves us from terrorism.
Any City In The Clouds
Most games with Cloud Cities give you limited space to roam,mostly restricted to evil lairs, military bases, and factories, and docking bays, but what if you go anywhere in this heavenly metropolis?
Canada
Can you name one game set in Canada, didn't think so. What's the deal, is Canada really that boring, with all the stereotypes you think any game developer would have a blast with it, but nope, no maple syrup power-ups for me.