For Slendytubbies III (the 2017 sequel), the developer briefly made the source available (C#/Unity) before going closed-source again. This led to confusion that ST2 might also be open.
A full ST2 source dump (often found on GitHub or Internet Archive) usually contains: slendytubbies 2 open source
Some releases are partial—missing certain prefabs or scene dependencies—but complete dumps allow a full recompile in Unity 5. For Slendytubbies III (the 2017 sequel), the developer
The confusion arises from several factors: Some releases are partial—missing certain prefabs or scene
The ST2 multiplayer mode uses a custom UDP-based protocol. Some developers have created open-source server emulators (Python, C++) that can host ST2 multiplayer matches without the original server binaries.