s&box

A host-authoritative day/night clock. The host runs time, clients follow it smoothly, and a paused host no longer leaves every client free-running through a whole day on their own.
Pure sun and sky grading. Give it an hour and the day's weather and you get a sun rotation and four colour grades back, exact at your reference hour, blended through twilight so dusk never snaps.
Deterministic per-day weather. Clear, cloudy or rain from a hash of your world seed and the day, so every peer agrees with no extra networking.
The sky seam. Four crossfade weights per hour that you feed to your own sky. The kit ships no sky shader and no sky art on purpose; the weights are the whole contract.
A dev time panel on N. Scrub the clock, change the pace, jump to dawn or dusk, pin the weather, hold time, and copy the tuned config straight to your clipboard as C# you can paste.
A demo scene. Four real minutes to the in-game day, so you watch a full cycle instead of waiting for one: the sun sweeps, the shadows swing, night goes properly dark. It also prints the live sky weights, which is the only way to see the seam working in a kit with no sky art.
An optional rain shower and an optional driver component that applies the grade to your light each frame. Both delete cleanly.
A self-test battery on fg_daynight_selftest that proves the maths without opening a scene.

Dragging the time slider all the way right could tip you into the next day and re-roll that day's weather. One in-game minute is not exactly representable in binary, so the quantized slider overshot midnight by a hair. It clamps now, and the self-test checks for it.