No revenue estimate for GOG — its rating/review counts don't calibrate to sales the way Steam's do. The Steam version is estimated at $35.7K — a different platform, not this one.

NAM

You are Alan 'The Bear' Westmoreland, Marine Corps sergeant. The trouble starts on a deadly Viet Cong raid. Here the jungle is your battleground. Your mission, survive. NAM captures all of intensity and paranoia of jungle warfare. Fire-fights, ambushes, booby-traps, snipers, air-strikes, anti-personnel mines AND MORE. Feel the tropical heat and the fear of tunnel skirmishes, paddy killing fields, swamps and thick jungles. NAM is the first game of its kind. NAM IS WAR! Experience the intense action and real ambience of the Vietnam war. Devastating air strikes, mines and ambushes. 34 single and multiplayer, gut-wrenching levels. Employ true-to-war tactics to survive. Incredible 8-player multiplay: 8 Gruntmatch, 6 Capture-the-flag and 5 Fireteam levels. True US military standard issue weapons and equipment; M60 Machine Gun, M79 Grenade Launcher, M16 Rifles, Flame-throwers, C4 Plastic Explosives, Mine detectors and much more...