What I've always wondered about game companies is how they can give out their SDKs for free. Examples: Source SDK and Unreal SDK.
Basically what I'm wondering is why Source and Unreal's SDKs are free when Torque 3D is $1,000. I know Torque 3D can be used to design games from the ground up, but if you know LUA, Blender, Hammer, Source SDK's choreography tool/face animator, and all the free software used for game design, couldn't you make a game comparable to HL2 from the ground up using free software?
Can someone who knows a lot about this please explain it to me?