Floor tile hiding spots

[Captain_Bravo]

Any tile with something underneath it should have a subtle, but visible sprite change. Also, sticking a grenade underneath should make a landmine. Imagine an assistant stepping off the arrival shuttle, and noticing that every single tile on the floor has been booby-trapped with something. Better hope they just stuck a pair of shoes under those tiles, John Q. Pubbie!

Despite the fun that could be had, though, I'm fairly sure this idea has been suggested and shot down before.