Scoreboard timer, tag, notperson, armorstand, lost series

[shiiiney]

Hello.

Me and my friends are trying to make some sort of countdown timer showed at the scoreboard. Which have to be resetted when pushing a button, so it begins over agian.

Our end goal is to get something like in the LOST series. We want a countdown of 20 minutes, and if no-one on the server presses a button before that time has passed, everyone on the server dies.
The countdown timer should not be on a person, i read on forums that maybe Armorstands could do the job. But we have no idea how to make such a thing. We've tried numerous countdowns but we're not that into commandblock, and need som help.

I hope some of you could help solve our problem.
TL : DR - 
We need:
1. Commandblock which makes scoreboard on etc armorstand's name
2. Testfor if 1200 seconds has passed - If yes, Kill @a
3. Commandblock to our base which resets the countdown.

[Razboy20]

I was just looking around the forums, and I stumbled upon your post.
For the armorstand, you could use this to add the armorstand: /scoreboard players add @e[name="name",type=ArmorStand] <objective> <amount>
and this to check: /execute @e[type=ArmorStand,score_<objective>_min=24000] ~ ~ ~ kill @a


To get 1200 seconds, or 20 minutes, you could add a repeating commandblock which adds 1 to a scoreboard, Basically, 1 every tick. And there are 24,000 ticks in 20 minutes, since that is the length of a Minecraft day. And to reset you can just set the scoreboard back to zero.
I hope this helps!

[LambdaPI]

Please do not bump posts that are greater than 2 months old.

Especially the fact that this post does not relate to redstone.