Half-Life: Delta Particles is a single-player modification for Half-Life.
Features include a new single-player campaign consisting of 4 chapters, total conversion, a lot of new content, the atmosphere of the new scientific complex "Delta Base", new weapons, a new Dark Ambient soundtrack and a BlueShift-style XEN level.
The plot takes place at the universe of HL. You're playing as a technical engineer of complex "Delta Base" Nick Farell. Unfortunately, the protagonist was in the wrong place at the wrong time, as an experiment at the Black Mesa Research Facility resulted in a resonance cascade that teleported extraterrestrial beings from the world of Xen to Earth.
