Okay, say that they have released an addon for Blender for modders. Because Blender is under the GNU GPL the addon they release has to be at the very least compatible with the GPL and therefor it should be Free Software. They wouldn't care. I mean if people can make mods, and improve the addon, it will be easier for them themselves to use it to make assets and everybody benefits. Typical "open source" mindset. And guess what? They did exactly this. Their Blender Addon is under a GPL compatible license ( MIT ). So okay, they at least developed one Free Software thing.

But if you look into it more deeply you will find more interesting things. For example, there is a Free Software python API to drive a special variant of BeamNG called BeamNG Tech. Which is for professional use. Yeah, well... This python thing still requires the proprietary BeamNG tech to be installed. But still. Here is another technically Free Software thing that they developed.

Then if you look even deeper, you will notice that they switched a game engine sometime in the early days of the game. First they used Cry Engine. Which is very proprietary and probably very costly. And then they chose to use a Free Software game engine called Torque 3D instead.

So they are building the game with Free Software on a Free Software game engine for which they built Free Software tools. And yet the game is still proprietary. Even though, as I already said, it feels more like what a Free Software game feels, with community collaboration and an insane level of customize-ability.

Applying this theory means , almost every software that has ever existed is free and open source.