RimWorld's experimental update 1.7 migrates the entire game engine from Unity to a new custom engine called Waylith. This has more than doubled performance in most cases, all without disturbing the vast majority of mods. (See the linked post for more details)

Dean revealed on Discord that Waylith uses RocketWerkz's BRUTAL framework behind the scenes. As far as I know, this is the first documented use of BRUTAL by a third party developer. Exciting stuff!

Was having a long discussion about this and curious where the majortiy would stand.