Half-Life: Critical Mass is a singleplayer mod for Half-Life: Opposing Force rather than just normal Half-Life. Critical Mass reveals the fate of Corporal Adrian Shepard - and also Gordon Freeman - in a manner consistent with all episodes of the Half-Life saga, including Blue-Shift and Decay, the co-operative game on the playstation 2 version of Half-Life.
Set in the Northwest Advanced Operations Facility, a military base where Black Mesa's research is being continued, the main enemies are the the Race-X aliens from Opposing Force, new-look half-life marines and male and female black ops, but you'll also go up against Gordon Freeman and the infamous g-man.
Uniquely, during the game aliens will not spontaniously teleport in anywhere, instead they can only appear in one location, the teleportation laboratory complex, where a raid by Black Mesa escapees has resulted in a leak in the displacement dampening system. The aliens will progress through the facility, complex by complex, area by area, while the military attempts to contain them and reclaim control. The mod will have at least three different endings and may even have five.
If you are interested in mapping, modelling or coding for this mod, please contact me at firstname.lastname@example.org . Note that for the moment no modelling or coding is needed. The architecture does not have to be brilliant – if you can make decent-looking corridors, laboratories, offices, or barracks, then you are good enough. Plotline, scripted sequences, combat and dialogue are the main thing – if the maps look about as good as the original half-life, that’s a bonus!