There are 2 repositories under source-sdk topic.
Cheat for Garry's Mod (x64)
A community-driven filmmaking tool built on Source. Pre-Alpha!
Original HL2 Source SDK from 2004
Bullet Physics Injection for Source SDK 2013
A Source Engine 2013 SP mod aimed to provide bug fixes and various development features
Portal 2 assets converted to use in Source SDK 2013
Team Fortress: Invasion brought over to Source 2013.
BrainBread 2 Source Code
Fork of Valve Software's SDK for Source Engine games with deferred lighting added.
My mod that adds some new features
Half-Life 2 Deathmatch Bug fixes (HL2DM Bug fixes)
A small library that aims to help with converting Valve's KeyValue (VDF) format to JSON and vice versa
Mobile Forces Source
Standalone ValveProjectCreator with some bugs fixing.
Grey Source 2021
A simple Blazor powered game server browser
Untouched Alien Swarm SDK for modern systems (CMake edition)
The SDK for Grey Source 2019, made to build on Microsoft Visual Studio 2019
In CS2, Nixware has a good legitbot and great visuals, making it a solid choice for clear and effective gameplay.
Generates and compares entity definitions from FGD data for backporting maps… made for porting csgo maps to css
A tiny launcher for Team Fortress 2 Classic on Windows, written in Rust.
Инструментарий для работы с файлами формата AIN(Valve SDK, GMOD, TF2 и др.)
[WIP] Mc-Source is a tool capable of converting Minecraft structures to Source-compatible maps.