I ran a d&d game for a group of friends where the room after the front door contained nothing but a closed stone door and a small raised plaque. If you touch the plaque, the front door closes and runes glow and start changing in shape on the plaque. This caused them to panic and they struggled for several minutes to figure it out. Their characters took turns touching the plaque as they attacked the door with weapons and magic. They attempted trap checks and arcana checks and failed some knowledge checks. After wasting spells and exhausting resources, they gave up and let the runes run their course. The stone door slid open after the sequence completed.
With all the commotion and wasted time, they allowed the enemies to fortify, plan, and surround them. I had a lovely time, but boy were they mad about the insignificance of the room. ^.^