> My experience with DLC on Steam is from a different engine.
> Easiest way is to include the additional content within the base game, and enable it after checking DLC has been purchased.
> It might be hackable, but less so than an easily copyable new file, and I'm not sure there really is a non-hackable option.
> Obscurity is a bigger danger to a games success than hacking/piracy anyway, so I wouldn't worry about it too much.
but that's anti consumer at it's limit, I don't think it's too great of a solution
How is that anti consumer? Or are you saying all DLC is anti consumer?
You've got to get the DLC content to work with the base game somehow, you're either going to have to overwrite files or put it somewhere the base game can access, so why not add it in an update to the base game but only accessible to those who buy the DLC.
A benefit of doing it this way is that in a multiplayer game you are able to show the content to all players not just those with the DLC, so everyone will know you bought the Shiny Hat DLC.