I own this game on Steam originally and recently bought it on GOG. After installing the GOG version and launching the game, I noticed my Steam client reporting my activity as playing BallisticNG despite the game not being installed via Steam and me running the GOG version.

I noticed steam_api64.dll (and steam_appid.txt) in the game's GOG installation directory, and deleting this file prevented the Steam client from detecting the GOG installation's activity.

I'm probably in a very small minority of players who have this "problem," but it does seem like unwanted behavior from the GOG version of this game, and the Steam.dll should probably be excluded from these builds (imho).

Love the game, btw!