1. StatekitDead simple, lightweight "states as objects" system
3. ZestkitTween library for Unity. The best of GoKit and GoKitLite combined in an easy to use API
4. P31unityaddonsMostly defunct. Features were added and components broken out in the *Kit repositories.
5. UtilitykitMostly static utility classes that are used across multiple projects. This seems like a better place for them than in Gists.
7. NezNez is a free 2D focused framework that works with MonoGame and FNA
15. SpriteKitDEFUNCT: Unity now has 2D tools built in. This is now not maintained.
16. MessageKitDecoupled message sending system meant as a replacement for SendMessage and its variants.
17. zig-upayaZig-based framework for creating game tools and helper apps
19. GoKitLiteA super duper lightweight tweening library for Unity