X-Tension was released in 2000, and details Kyle Brennan's establishment of TerraCorp and the events following the Xenon war and the first expansion into the new Sectors. It uses the original X-BTF engine but adds some features and corrects some issues that were experienced with the previous game.
It was succeeded by X2: The Threat.
There is no over-arching plot, unlike each other game in the X-series, but there are a number of 'quests' that the player could achieve, the begginnings of what would become NPC missions in the later games.
The map was expanded to 90 sectors, with former Xenon space becoming a lawless, neutral Pirate bloc.
The game introduced the ability to move between ships, which was lacking in the original.