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s&box

Modern game engine built on Source 2 from the creators of Garry's Mod

paid TBD, Steam release April 2026 Solo-dev friendly

s&box is a game creation platform by Facepunch Studios, built on Valve's Source 2 engine with a modern C# API. It includes a scene editor, Hammer level editor, visual scripting, and a cloud asset library. Source code is open under MIT, and games can be exported as standalone Steam titles royalty-free.

Highlights

  • + Built on Valve's Source 2 engine with modern C# scripting and hotloading
  • + Full editor suite including scene editor, Hammer, and visual scripting
  • + Export standalone Steam titles royalty-free
  • + Play Fund revenue model lets creators earn from player engagement

Limitations

  • Still in early access — full release expected April 2026
  • Underlying Source 2 engine code is proprietary despite MIT game code
  • Smaller ecosystem compared to established engines like Godot or Unity

Platforms

Windows