The X-Files: Resist or Serve is a survival horror game played from a third-person perspective that is viewed by the player through fixed camera angles that change as the character enters each new area.[8] The player chooses to play as either Mulder or Scully; both go through most of the same locations, but they encounter different obstacles and characters that result in a different gameplay experience.[9]
A total of five guns can be used throughout the game, as well as other weapons such as molotov cocktails. Additionally, the player may use a flashlight to stun enemies and easily locate items in the environment that are needed to progress through the game.[10] Also located throughout each level is gun ammunition and items that can replenish the player's health.[10] Items and ammunition are sometimes carried by enemies, who must be killed before the item can be obtained by the player. Weapons, ammunition, and other items are stored in an inventory.[10]
Boss enemies are encountered in each level and must be killed by the player before proceeding.[10] Puzzles must also be solved to progress through the game.[11] Throughout the game, Mulder and Scully write notes about their investigation that may be viewed by the player at any time.[10] Playing as Scully, the player is sometimes tasked with performing autopsies on bodies or with creating antidotes for toxins.[8]
