All Product Lines from Operational Studies Group (OSG)
OSG games are considered 'kinda' quirky by the majority of wargamers, but those who have actually played them know they are totally revolutionary. Either you agree that the revolution was necessary and you join it, or you see no need for all the fuss and hold to tradition.
OSG games are among the best kept secrets in plain sight. A select few get it. You have to play it wrong the first time. Then, instead of blaming the game, realize, "o.k., I see, let's start again." You play it again, but you still have that feeling, "I think I could do better ..." Mastery comes slowly, and the game is never the same twice. That itself is surprising given what people have grown to expect in this hobby.