I think it might be _unethical_ to not spread the joy of playing Doom for the first time? Though, I’m not entirely sure there’s been enough research done about the effects of violent video games in rat gamer populations.
We've been putting rats in skinner boxes for a lot longer than we've been subjecting human gamers to them. I'd be more worried about the health effects of all that sugar water.
Giving them slightly acidic water off-rig and normal water while playing is another option - not the best either. I opted for sugar in the end, because they didn't spend much time on the setup; but this should be reconsidered if they on-rig for hours daily.
It's more like locking humans up in the matrix. Note lines like "preventing it from leaving the apparatus" in the build guide. Would an ordinary gamer be restricted from exiting such a contraption?