That's an absurd proposition for most people. Rolling out our own worked for Minecraft. It also may work for bigger companies (Frontier Developments, Bethesda?)

That's an absurd proposition for most people. Rolling out our own worked for Minecraft. It also may work for bigger companies (Frontier Developments, Bethesda?). Successful releases using open-source engines are rare. For the overwhelmingly majority, they are much better off just using one of the big game engines, even after paying them.