On my server I have a quiz which you need to take before you can go to most of the areas, build etc... However, sometimes people try to cheat by going with friends into there. I want some kind of gate/mechanism which only allows one player to pass through and insert some kind of delay or so after this. Is this possible? For the delay I know how to make it, I only need to know if you can build something where only one person can pass through, not multiple at once.

  • 3
    Command blocks would be the closest thing to provide this functionality. You would have to teleport the player, but the problem is knowing which player to teleport.
    – MBraedley
    Commented Nov 16, 2012 at 3:00
  • @MBraedley Well, that doesn't really matters... The one who don't gets teleported simply has to wait until the other one finished.
    – Andalur
    Commented Nov 16, 2012 at 3:05
  • 1
    @MBraedley You should post that as an answer. It's probably even more solid a solution than mine. Commented Nov 16, 2012 at 4:11
  • What's to prevent people from instant messaging their friends to get the answers?
    – John
    Commented Nov 16, 2012 at 13:36
  • 2
    @Andalur I'm confused. I don't see how you're going to set permissions on skype/google chat/cell phone IMing/etc.
    – John
    Commented Nov 16, 2012 at 16:04

4 Answers 4


I think the answer from MBraedley is correct: the best way to handle this scenario (allowing access to a single player at a time) would be to use Command Blocks to teleport one player into and out of your quiz area. You can program a Command Block to teleport the nearest player to a set of coordinates like so:

/tp @p x y z

I don't know what would happen if two players somehow managed to be the exact same distance from the command block (i.e. does just one get teleported, or do they both get teleported since there is a tie for the "closest"). This additional argument may be necessary to limit it to only one player:

/tp @p[c=1] x y z

The next step is to create a circuit whereby clicking an "entry" button will teleport one player into the quiz area, deactivating this button so that it cannot teleport anyone else in until the player exits the quiz area by clicking a second "exit" button, teleporting them out. Here's one such example circuit I just threw together in my survival game:

enter image description here

The blue blocks are buttons that feed their signals into AND gates (green blocks). The outputs of the AND gates will activate Command Blocks (shown here as redstone lamps at the bottom of the image) and will also feed into the input of a T flip-flop circuit (red blocks). The output of the toggle circuit runs behind the red blocks and feeds into an input of each of the AND gates.

When the toggle circuit is in the "off" state (no output, as shown in the image) then the signal from the right button is disabled and the right redstone lamp (i.e. Command Block) cannot be activated. Activating the left button will cause the left redstone lamp to activate and immediately flip the toggle to the "on" state. This will subsequently disable the signal from the left button and reenable the signal from the right button.

This circuit should give you the ability to allow one player at a time to teleport into your quiz area via a button press. Once they reach the end they can then press another button to teleport out and reactivate the entry button for the next player. I'd also suggest enclosing the circuitry and your quiz area in bedrock, so your average player can't mess with any of it.

  • The new testfor command is probably useful here. If there is more than 1 person in the test area, teleport them all back to the spawn area.
    – MBraedley
    Commented Mar 15, 2013 at 18:10

You might want to consider using command blocks to teleport players from a spawn area to the quiz area, and then again to the player area. The reason I'm suggesting teleporting the players into the quiz area is that you only want one player there at a time in order to ensure that the player that finishes the quiz is the player that's teleported to the playing area. There are a few ways to check if a player is still in the quiz area and hasn't, for instance, logged out.

As for how to actually implement this, I have no idea. Obviously, you'll need to have at least op powers so you can spawn the command blocks. Beyond that, I can't give many details.

  • You also have to enable command blocks in server.properties - but the line isn't there until you try to use command blocks, which you can give yourself with the /give command. The ID is 137.
    – Timtech
    Commented Jul 26, 2013 at 22:00

Iron doors with a button will make them impossible to open until the player passes the quiz and steps on a pressure plate, which will then allow the doors to open again.

  • Not if the second player has a button/pressure plate/any other door opening device that can open the door.
    – user28379
    Commented Nov 18, 2012 at 1:37

You can use a testfor command that is on a clock and from the command block is comparator that goes to iron door that is closed as if it was opened and if player enters iron door, it closes and anyone other cannot get in until he/she leave

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