…but the backdrop cannot be taken. I have a custom message for them trying to take it, and this is overriden if they try to eat it ((first taking the sand) “That’s hardly portable.”) Will this need to be a special rule?
I did something similar (allowing the player to eat a room) and just did a rather elaborate workaround. I think it would work for you too, especially if it just kills the player which eliminates dealing with any aftermath in the gameplay.
Actually, this simpler solution could work:
before eating backdrop: say “You’re dead!”; end the game; stop the action.
That worked like magic, thank you! First time using “before”, it didn’t even enter my mind 
Alternatively you could lace the backdrops with delicious poison, for a much slower and more romantic death.
It might be better kept secret that you want to kill players. Otherwise, they might not play your games. 
Good point, but it’s pretty easy to avoid dying in this particular game: I just want to kill them as a sort of smack on the bum for doing something profoundly silly and annoying
Reminds me of a game I wrote in which there is a bucket lying around. Just in case some smart-ass player tries to kick the bucket – he kicks the bucket!
Robert Rothman
Sorry for my obscure joke - of course you are killing player characters, not players…
I laughed.
You mean that I shouldn’t have used the special function which shorts the high-voltage power supply to the keyboard? Uh-oh, I think I may be in trouble now. 
Robert Rothman
I swear there used to be a warning in xconfig files that improper settings could cause the monitor to explode. Neal Stephenson commented on it with a character called the “Digi-bomber” in Cryptonomicon, and I’ve heard similar stories have been used elsewhere. But folks on Snopes say it’s very unlikely:
I laughed too! lol 
I often want to kill players who do stupid things with obviously non-interactive scenery. This actually makes me want to play your game (carefully).