KittyMineCoin

Just like Bitcoin, $KMC is a layer-1 digital currency but has been implemented through a shared chat log common in many modern video games. $KMC simply uses a syntax specific to the Minecraft chat log for retrieving transactions and blocks that players hash.

Implementation of this system in other games is very easy. As KMCoin runs currently, it consumes only 1Mb of RAM, generating trivial energy cost. The program itself is only half a megabyte and can run endlessly on any PC capable of running Java 8 and Minecraft for 146 years, given it can store 1Tb of information on the drive after this 146 year period.