Competitive advantage. On the PS4 at least, Doom 2016 and Doom Eternal are the some of the best-looking games which are capable of running at a constant 60FPS o

Competitive advantage. On the PS4 at least, Doom 2016 and Doom Eternal are the some of the best-looking games which are capable of running at a constant 60FPS on the platform. Additionally, the team will have a tonne of institutional knowledge built up over the engine's lineage and content creation tooling, making switching a costly proposition. It's worth noting that after Carmack's departure, the engine development is now headed by Tiago Sousa, the guy responsible for the Crytek engine. He's very much a worthy successor IMO. Perhaps a more historical point of owning the rights to your own engine is the ability to relicense it under something like the GPL for others in the community to learn from (once it has outlived its useful commercial life). Id is well known for doing this (see their GitHub repo), driven by Carmack's altruism, and there is a thriving community of ports and code review breakdowns (Google Fabien Sanglard) for their historical products as a result. It's unfortunate that this trend did not continue past Doom 3.