Is Adventurer Conqueror King a Retro-Clone?

One question we get asked a fair bit is whether the Adventurer Conqueror King System (ACKS) is a retro-clone. ACKS is not a retro-clone in the sense that it doesn't seek to replicate the experience of any particular rules systems. But it is built upon the excellent foundation that was laid by the retro-clones, in particular by Dan Proctor's Labyrinth Lord and Chris Gonnerman's Basic Fantasy RPG, without which our own work would have been vastly more difficult.