The COLX 'ZERO FEES' option isn't 'planned', it's already built in to COLX and is live now!

parnum
The transaction will only go through if a block is not full, as you're not providing a miner's fee. I don't know the throughput level of COLX, but with only a few transaction in the blocks that I had inspected, the blocks seem to have a lot of room left for zero-fee transactions.

In the future, if there is more transaction volume than the blockchain can handle, then getting zero-fee transactions through will take some time.