This first mechanic is based around an egyptian theme. The mechanic has two features: a door, or a puzzle. If used as a puzzle, we suggest that the pattern on the roof is removed and clues to the pattern are hidden around the rest of the map. The mechanism is 100% fool-proof. The mechanism works as so:

1. The player enters
   
2. The door closes behind the player and their gamemode is set to adventure
   
3. The player then enters the code using the pressure plates on the floor
   
4. If the code is incorrect, the player is killed
   
5. If the code is correct, the door opens
   
6. The player then exits
   
7. The door closes behind them
   

The reason we like this map is because it contains no tripwires, pressure plates (apart from the ones for the code), levers or buttons. The door will not open unless the code has been complete and the player cannot pass through without it. The mechanic can also be turned on and off with the flick of a lever. 

{Disclaimer} This mechanic was created by MonkeyMaster10 and is free for anyone to use in their map. I ask that if you put it into your map, that you link this thread in the map description... Thanks :)