I'm building self regenerating mini games for Minecraft and I had an idea for tnt run. Originally I just had pressure plates activating TNT, but I had an idea that would make it look like the Spleef on cube craft. I started off by making a repeating command block (always active) with the following command:
execute @a ~ ~ ~ /testforblock ~ ~-1 ~ stone
I hooked this up to a chain command block (conditional, always active)
/execute @a ~ ~ ~ /setblock ~ ~-1 air
However, I found that it removed the block too quickly, so I put a comparator in the middle, but the same thing happened except the blocks were deleted slower yet still directly beneath the Player. I tried hooking it up to a clock and replacing the test for block command block every time it found stone, but I don't know the block NBT data for always active. All that I can think of other than hooking up different kind of clocks.