Night
That's a great idea! You're running around the map and suddenly see drunk or not-so-drunk thieves near bags of gold. You think, "They must have stolen it somewhere, I'll give them a good beating!" You run up to the group... and they run away in terror :eek:, disappearing from the map ;)
By the way, gems and crystals should also be guarded. Stones, wood, and sulfur are unlikely to be of interest to neutral creatures... and mercury is even poisonous! :cool: