Free FPS on Half Life engine gets big update

A new version of Diffusion has been released. It’s a standalone mod built on the foundations of the first Half-Life. Last year, ModDB users voted this project the second best mod of 2025.

The game is a singleplayer FPS that takes us into a new futuristic universe, where we play as a SWAT veteran who becomes accidentally entangled in mysterious experiments. The project is built on the Half-Life engine, but everything here is new — maps, assets, enemies, and weapons. The gameplay mechanics are also significantly different, having been modernized and enriched with some elements taken from tactical shooters.

Although the project is technically a mod for Half-Life, in reality it is completely standalone, so it’s essentially sa free game.

1. Download Diffusion from our FTP (the developers have granted us permission to host a mirror).

The new version of the mod (1.1), brings many changes. The most important ones include:

1. All voice acting has been replaced with new recordings of much higher quality.
2. Graphical elements on many campaign maps have been improved.
3. Enemy AI and weapon balance are now enhanced.
4. Numerous bug fixes have also been implemented.

Diffusion was one of the most pleasant surprises of last year. It is essentially a free game with a level of quality comparable to many modern commercial boomer shooters, so if you haven’t had a chance to play it yet, it’s definitely worth giving it a try.

Half-Life

November 19, 1998

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• Half-Life (franchise)
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