Steam Deck games: X
- X InvaderPlayable
- X Invader: ProloguePlayable
- X RebirthPlayable
- X-COM: EnforcerPlayable
- X-Morph: DefensePlayable
- X-MutationPlayable
- X-Out: ResurfacedVerified
- X-Plane 11Playable
- X3: Terran ConflictPlayable
- X4: FoundationsVerified
- Xanadu LandPlayable
- Xander the Monster Morpher: Universe BreakerVerified
- Xanthiom 2Verified
- Xanthiom ZeroVerified
- Xaphan - Battle SimulatorPlayable
- XCOM: Enemy UnknownPlayable
- XCOM® 2Playable
- XCOM®: Chimera SquadPlayable
- XeGrader plusVerified
- XELVerified
- Xeno CrisisVerified
- XenoHavenPlayable
- Xenon RacerVerified
- Xenon-RunnerPlayable
- Xenonauts 2Playable
- XenosensoryVerified
- XenosisPlayable
- XENOTILT: HOSTILE PINBALL ACTIONVerified
- XenoTownPlayable
- XenturePlayable
- XeodrifterPlayable
- XetanonPlayable
- XFlight: FPV Drone SimulatorPlayable
- Xiangsheng SimulatorVerified
- Xiaye's Doors of Magic: LightchaserPlayable
- XIIIVerified
- XIIZEALPlayable
- XING: The Land BeyondVerified
- xiuzhen idlePlayable
- XiuzhenWorldPlayable
- XiuzhenWorld2Playable
- Xmas ApocalypsePlayable
- Xmas, Super Puzzles DreamVerified
- XO EvolvedPlayable
- XOL: Space Mech WarsPlayable
- Xuan-Yuan Sword VPlayable
- Xuan-Yuan Sword: Mists Beyond the MountainsPlayable
- Xuan-Yuan Sword: The Cloud of HanPlayable
- Xuan-Yuan Sword: The Clouds FarawayPlayable
- Xuan-Yuan Sword: The Scar of SkyPlayable
- XXX_CYBERRAT_XXXPlayable