I got into 28mm Modern Afghanistan by accident. A friend named John Gonzales had some 28mm Taliban insurgents from The Assault Group he wanted to get rid of. I bought them at a Die Con convention several years ago. I went ahead and painted up the Taliban and bought two squads of US Marine infantry. I then proceeded to get Chain Reaction 2.0 for a set of rules. They worked. It was hard trying to figure out the reaction rolls to the reactions of other figures.
Steve Hood and Joe Collins then discovered Ambush Alley. I downloaded the basic rules - Ambush Alley "Contracting Trouble." I use them for 28mm Modern Afghanistan. I've also played Face of Modern Battle about eight years ago with Devil Dog Design figures. The rules weren't to my taste.
Ambush Alley is based on quality dice and reaction rolls. The better the unit, the larger the quality dice. You dice off squads against each other and that determines casualties. You then roll for the results of casualties at the end of a turn. Reenforcements and entry points for insurgents are random. The game is scenario driven. I have a Humvee and a downed Black Hawk helocopter and crew from Britannia Minaitures (out of their old Somalia line). I've run all sorts of scenarios for the American players from Black Hawk down to a person of interest scenario. I've also had a scenario to remove a rocket launcher from a Taliban strong hold. The American player in charge failed his rolls to call in Apache air support to take out the rocket launcher. All the US Marine fire teams wound up being KIA or WIA because of Taliban reenforcements. No two Ambush Alley - Contracting Trouble games are ever the same. My 28mm Middle Eastern buildings for the Sudan/Egypt also double for Afghanistan.
Everyone else I know in St. Louis, MO who has moderns uses 20mm figures. That makes sense for the vehicles and figures available in that range. My figures are all 28mm. My terrain is in 28mm. It makes sense for me too keep my 28mm Modern Afghanistan. I'm also a British colonial gamer. Many of the modern scenarios play like a 19th century colonial game. I would like to get some more 28mm Taliban insurgents and maybe some more US Seal teams. But I haven't run a 28mm Modern Afghanistan scenario recently.
I do sometimes have regrets for gaming this conflict. I have known many acquaintances who have served in that theater of operations. It's rather weird when I'm running a 28mm Modern Afghanistan scenario and one of them comes up to me and tells me about their time in country. I don't have this problem with the Cold War or Vietnam games I've played. Then again, I actually like gaming Vietnam. Go figure...