Scalatron is another great one <a href="https:&#x2F;&#x2F;scalatron.github.io&#x2F;" rel="nofollow">https:&#x2F;&#x2F;scalatron.github.io&#x2F;</a> &quot;a free, open-source programming game in which bots, written in Scala, compete in a virtual arena for energy and survival&quot;