Great tutorial! It clears up a lot of my questions about various effects.

Minor complaint: Focal length is size of the lens. Focal distance is the distance between the camera and the focal point.

Describe the problem you are trying to solve.
Adopting Flecs would be made easier if prebuilt binaries were available for the CI platforms.

Describe the solution you'd like
A configuration that makes binaries available for a CI that supports it.

https://github.com/LambdaHack/LambdaHack/blob/v0.9.5.0/engine-src/Game/LambdaHack/Client/State.hs#L39

The newtype probably needs to be fully transparent, because the epsilon is used and created in many ways that are not easy to capture in a few combinators. The hardest part would probably be to find home for the type, unless the module above is by chance visible from all use sites.

Right now the player can bring his whole faction to a combat mission. Instead we should allow him to add eight characters to a squad which will then be used when loading the combat mission.