I'd like a Tears of Fukishima setup where language barrier was a major gameplay mechanic. Almost no STALKERS would speak Japanese because it's relatively difficult for Japanese nationals to get their own guns. To go around the "They could just buy them in the zone" thing, we could say the zone is very young, and the artifacts out, guns and supplies in economy is in its barest infancy making guns scarce. Ukranian/Russian STALKERS would also be present, and some of if not the strongest STALKERS due to their experience. You could start with one language (English, Japanese, Russian, Chinese, Korean, and Spanish would be a good set to start from) which would be a combination of difficulty setting, start location, and faction relation setting. Starting as a Japanese speaker would make getting food, supplies, and maybe leaving the Zone for a while much easier, but it's going to be hard to get a gun. Speaking English means that it's pretty easy to find a seller for high quality weapons and munitions, but everything else requires a lot of work to get people to trust you or bother helping you, and actually getting the money to pay for the stuff will be harder. Speaking Russian would likely make it easier to survive since you could communicate with experienced STALKERS on the field and have easy access to low-mid range gear, but supplies will be hard to come by. Chinks and Chinks in denial and Flips would be hardmodes.