Players can attempt to hinder their opponent's investigation by playing Events, Bluffs, and Adversary cards from their own constructed Bureau Decks.

Each round, or turn, in the game is composed of seven phases: Briefing, Healing, Requisition, Deployment, Case Assignment, Investigation, and Debriefing.

[11] With the sale of Donruss to Pinnacle Entertainment, the licensing rights were transferred to the United States Playing Card Company (USPCC).

[11] Over the next year, USPCC would create the first expansion, codenamed 101361 (after Fox Mulder's fictional birthday), a 2nd edition set known as The Truth Is Out There, and a number of promotional cards.

A second expansion, codenamed 22364 (after Dana Scully's fictional birthday) and comprising roughly 138 cards, was in development when the game was terminated in early 1998.

[13] The following editions and expansion of The X-Files CCG were developed and released by USPCC: A couple hundred copies of this 60-card demonstration deck were used at Gen Con '96 to attract potential players.