nSDK is a Windows-only extension SDK for Clickteam Fusion 2.5. I created this to learn more about the inner workings of Fusion extensions, as well as solve some personal gripes I had with the official SDK. It uses the same headers/libs from Fusion 2.5 SDK, but modified to incorporate newer Fusion additions, & the template is a brand new Visual Studio project rewritten from the ground up instead of using the official template provided (which, at the time of writing, is still a VC++ 2005 project).
The entire goal of this SDK is to make some error-prone things (like defining A/C/Es) easier & safer while also keeping abstractions at a minimum to provide the most flexibility and performance possible. Some of the extension exports are implemented by the SDK itself but is still available to every extension so they can add their own behaviors on top if desired.
As a curiosity I have also made (crude) SDKs for obscure types of extensions; namely filters & transitions. Clickteam has made futile efforts in documenting these (either vaguely documented, entirely unreleased, or no longer available at their website), so the development of these SDKs is mostly just the result of trial, error & guesswork.
Clickteam for the Fusion 2.5 SDK, headers/lib originates here with modifications
DarkEdif SDK, where I got the DX11 additions from