Diffusion

Diffusion completely reimagines the visual aspect of the classic engine: improved materials, dynamic lighting, realistic shadows, water with reflections, and a set of effects that make the world simultaneously modern and nostalgic.

The story premise is as follows: you are James Smith, a special forces veteran with ten years of impeccable service. On vacation, you're driving to a quiet place to rest from your usual routine. On the road through deserted Utah, your car breaks down. Deciding to move forward, you stumble upon an abandoned stone and sand processing plant, where only one guard sits. Following his directions, you go behind the factory building in search of a phone. Returning, you see only two army trucks and a dead guard... Curiosity leads you inside the factory, where it turns out that this facility hides much more than it seems at first glance.

The gameplay combines familiar Half-Life elements with a number of modern mechanics. Shooting has become more dynamic — there's a sense of recoil and rhythm, enemies demonstrate tactical maneuvers, and the player has a wide arsenal and special abilities at their disposal (for example, a new suit with dash and electro-pulse, a drone, and deployable turrets). Puzzles are organically integrated into the levels and more often use the environment rather than simple "press a button" solutions, making exploration of the game world useful and interesting.

The sound design and character voice acting fit well into the atmosphere — background noises and music work to create mood in each location, from windy peaks to gloomy dungeons. At the same time, localization and the quality of some voice acting noticeably vary — this doesn't interfere with perception, but sometimes breaks full immersion.

The levels demonstrate a variety of scales and styles: from cramped, detail-filled rooms to open, visually rich spaces. The map design tries to explain the purpose of each zone — even small objects look appropriate and help piece together the story. There are large memorable scenes, including vehicle control and water sections.

There are also controversial moments: sometimes it feels like there are too many weapons — some early samples quickly lose relevance, leading to cluttered slots. Also, there are rare bugs with collisions and minor graphical flaws, and the difficulty balance occasionally jumps. Nevertheless, the mod remains very engaging — the approximate campaign length is several hours of story playthrough, with potential for replays for better exploration of levels and secondary objectives.

Overall, Diffusion is an impressive technical and creative project, showing what can be achieved by using Xash3D's capabilities to the maximum. This is a mod with a vibrant atmosphere, rich gameplay, and strong visual component, which is definitely worth playing for fans of large, well-designed total conversions.