Whippet
I made a semi-cache coherent container which provides an Entity-Component-System. These are the bones of contemporary game-engines.
This post is a bit crude; I keep thinking about it then adding features to Whippet instead of writing this up.
Whippet on GitHub Google built CORGI which isn’t (yet?) trying to act cache coherent. It also is more than trivial to build, and suffers from NIH for me. Actually; that last bit isn’t likely to be a problem for most, but I didn’t like their license.