SampSharp.Sdk is the recommended starting point for developing open.mp gamemodes with SampSharp. It is a metapackage that bundles all of the core SampSharp libraries, the entity-component system (ECS) framework and command system, analyzers, code fixes, and the source generator into a single convenient package reference.
SampSharp is a toolkit that allows you to write gamemodes in C# for open.mp servers using the .NET runtime. SampSharp's aim is to provide all features of object-oriented programming and modern .NET development.
For general documentation and guides, see https://sampsharp.net.