VTMB HD Overhaul

Half-Life: Dark Matter is a single-player campaign for Half-Life that stays as close as possible to the series' canon. In it, you play as a Black Ops operative who gets caught up in the Black Mesa events during the resonance cascade and tries to deal with the chaos.

Command & Conquer Unofficial Patch — an unofficial update for the original Command & Conquer game (1995). The patch aims to improve compatibility with modern systems, fix bugs, add support for multilingual versions and high resolutions, as well as provide tools for creating custom missions and modifications.

OpenNox is an open-source game engine that is the result of collaborative community work. Its main goal is to extend and improve the original game Nox.

HLFX: Lost in Black Mesa is a short single-player mod for Half-Life based on the updated HLFX engine, featuring enhanced graphical effects and classic gameplay. The mod tells the story of Alex Jones, a young scientist who finds himself in an HEV suit on the day of the disaster.

Triphammer is a standalone mod based on an early build of Half-Life Alpha v0.52, which was previously available only to journalists, and transformed into a fully playable game.