Either contra-rotating, or NOTAR (image 1) helicopters as an addition to the game.
Best suited for SAR, as the rear rotor is excluded, decreasing risks realistically.
Though would love to see an attack helo to carry the perks of not having a rear rotor, an example would be the KA-50, or a fictional NOTAR, like the Patlabor's AFH-028 Hellhound (image 2)