[Rainbow Six]

When I was actively playing (which is now well over ten years ago), we didn't have any PC's that were current SF in our regular campaign, although we did have one US Army Sergeant First Class who was Ranger qualified (he broke both his legs in a parachute jump that went wrong in 1996 and the docs said he couldn't jump again, so he was transferred out of the 75th Ranger Regt and into the 5th Dvn just in time for the War in Europe) and one NPC who was a West German Fernspahtruppe.

There was no specific ban on Green Berets, SAS, and such like, it just never happened...(players were expected to come up with a plausible back story as to how their character ended up in Kalisz in August 2000 so that might have had something to do with it...personally I'd struggle to justify a realistic reason why a Green Beret Lieutenant Colonel (for example) would end up with a squad of 5th Dvn riflemen).

The group very occasionally encountered NPC SF types (such as a US Army Green Beret Captain who was working with one of the Polish Free Legions - the one that was in the north, I think the 2nd?), but I always tried to make such encounters rare, so that meeting a SF soldier was something that would stand out as something a bit diifferent...

Our Persian Gulf campaign was a little different (which was the intention to be fair)...SF types were much more common, both PC and NPC. Mind you, the Persian Gulf games always seem to run out of steam relatively quickly and we'd abandon our munchkins to come back to Europe and the more fleshed out, rounded characters we had there).

For the bigger picture, I go along with the view that in the year 2000 any remaining SF characters who have gone through all the required pre War qualifications, etc would be kept in reserve to be used as a strategic asset by Corps / Army HQ (or higher - I don't think it's too much of a stretch that any existing SF in CONUS might report directly to the Chiefs of Staff?).