What&#x27;s interesting here, is that they seem to have actually started with Lua, but then switched to a custom language at some point. I&#x27;m not quite sure what were the exact reasons, as googling leads to a github wiki which since &quot;has moved&quot;, but there&#x27;s some discussion in an earlier HN submission [1]. That said, personally I can&#x27;t say I&#x27;m really convinced (although I&#x27;m not a game programmer by any means).<p>[1] <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=7209149" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=7209149</a>