How to kill players that step on an iron block?

Question

I am making a map and I need to kill any player that steps on an iron block, but the commands aren't working. Here are the commands:

• Prequisites:

  /scoreboard objectives add IRONDEATH dummy
  /scoreboard objectives setdisplay sidebar IRONDEATH
  

• Repeat always active command blocks:

  /scoreboard players set @a IRONDEATH 0
  

• Chain always active command blocks:

  /execute @a ~ ~ ~ detect ~ ~1 ~ iron_block 0 /scoreboard players set @a[c=1,r=1] IRONDEATH 1
  
  /execute @a[score_IRONDEATH_min=1] ~ ~ ~ /kill @a[score_IRONDEATH_min=1]
  

Answer 1

The error is with your detect coordinates. ~ ~1 ~ means 1 block above the player's position, rather than 1 block below which would be ~ ~-1 ~.

If you don't need to do anything else with the IRONDEATH score, you could also simplify this down to:

execute @a ~ ~ ~ detect ~ ~-1 ~ iron_block 0 /kill @a[c=1]