I remember first seeing such a proof-of-work in the network protocol layer of the game Tribes 2. They opened up the source code for that, named OpenTNL (seems abandoned now) where you could see how it&#x27;s done. Here&#x27;s the part that verifies a puzzle:<p><a href="https:&#x2F;&#x2F;github.com&#x2F;kocubinski&#x2F;opentnl&#x2F;blob&#x2F;master&#x2F;tnl&#x2F;clientPuzzle.cpp#L107" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;kocubinski&#x2F;opentnl&#x2F;blob&#x2F;master&#x2F;tnl&#x2F;client...</a>