Invasion 1944 is a historically accurate World War Two total conversion mod for ARMA 2: Combined Operations(ARMA2 + Arrowhead) centering on the European theater.
You can't get much better than this mod when it comes to realistic ww2 combat simulation. Especially as a fan of the battle of the bulge, but also for ww2 enthousiasts in general this mod is a must have if you're into the realistic combat the arma 2 engine has to offer. Hopefully a full port to arma 3 will revive the community a bit, but that's something for the future. As of now, just give it a try, it's amazing.