About
Counter-Strike began as a free Half-Life modification (versions like 1.5, using the Rad-Therapy renderer); the project's disclaimer notes this differs from the standalone version currently sold on Steam. FreeCS (also called Tactical-Retreat) is a reimplementation, built on the FTEQW engine and the Nuclide SDK, that lets players run the original free Half-Life mod Counter-Strike 1.5 with the Rad-Therapy renderer. It requires the original Half-Life data files, is released under the ISC license, and supports Windows, macOS, and Linux.
Getting started
Requires FTEQW, the Rad-Therapy package, and the released cstrike content package, placed into the Half-Life 'valve' and 'cstrike' folders respectively; updates are then handled through the engine's own configuration menu. It will not work correctly with the paid Steam release's data — only the original free CS 1.5 mod data is supported.