The classic, era-defining Homeworld and Homeworld 2 got an impressive re-release in 2015 in the Homeworld Remastered collection, followed last year by a splendid (if low-key) prequel game, Deserts of Kharak. Missing from these celebrated events was Homeworld: Cataclysm, the stand-alone expansion for the original game.
Developed by Barking Dog Studios and released in 2000, Cataclysm has widely been praised as the best game in the series, with a tense, escalating storyline seeing the galaxy consumed by a cybernetic terror known as the Beast and the crew of a single mining ship desperately trying to find a way of defeating it. The game expanded on the original title's mechanics, introducing much-needed timeskip features and a lot of new ship designs. Homeworld 2 (2003) ignored many of the developments in the game, with a feeling among fans that the original designers at Relic (now at Blackbird Interactive) didn't really consider Cataclysm part of the official Homeworld canon.
Remastering Cataclysm proved impossible as the original source files had been lost, with the alternative - rebuilding the game from the ground up in the Homeworld 2 engine - considered too complex and time-consuming for what would probably be a limited return. Instead, Blackbird and Homeworld IP owners Gearbox have focused on getting the original game compatible with modern PCs and overcoming a major legal hurdle, namely that Blizzard bought the trademark on the Cataclysm name for a World of WarCraft expansion. The technical stuff done, the game is now available on GoG under the name Homeworld: Emergence to overcome the legal hurdles.
As one of the very best space strategy games ever made, I strongly recommend it.