A moral question in regards to the Advanced Combat System

I’m thinking of making a mil-sim game like Arma, so that instead of every milsim group needing to make their own map, they can all come on to this game. I decided to use the Advanced Combat System for the guns, and I was wondering in what way I should go about crediting, even if they don’t know it, one of the major members of the team? Is it moral to use ACS at all?

ACS is open-source, so if you want to use it go for it. Using ACS might make your game seem a bit “free-modeley”, though.

As for crediting the creators, putting their names in the game’s description should be fine enough.

all milsim groups use it asdfasdasdasdasdasd