Here’s what I came up with in 5-10 minutes for the 1HDC. I will try using the 50 left for other Ideas. It is self-explanatory, you can’t leave your room without turning the lights off.
The evident physical obstruction makes the user aware (I definitely hope so) and invites him to think in terms of causes and consequences.
I was intially thinking to install a floor tazer, but hey, the whole goal is to save electricity no?