Best Sci-fi Games Under $20

The 25 highest-rated sci-fi games you can get for under $20, ranked by Steam reviews, with the cheapest key across 21 stores.

  1. #197% of 91,157 Steam reviews
    Half-Life 2 game key cover art

    Half-Life 2

    $9.99 -29%
    $7.05
    kinguin & 11 stores
    2004
    FPSActionSci-fi
    Steam97%
    Achieve69
    Deckplatinum
  2. #298% of 26,814 Steam reviews
    Star Wars: Empire at War game key cover art

    Star Wars: Empire at War

    $19.99 -3%
    $19.28
    g2a & 5 stores
    2006
    StrategyRTSSpace
    Steam98%
    Deckgold
  3. #396% of 59,135 Steam reviews
    Half-Life game key cover art

    Half-Life

    $9.99 -3%
    $9.60
    gamivo & 12 stores
    1998
    FPSClassic1990's
    Steam96%
    Deckplatinum
  4. #497% of 21,442 Steam reviews
    Signalis game key cover art

    Signalis

    $19.99 -30%
    $13.99
    steam & 10 stores
    2022
    Survival HorrorPsychological HorrorFemale Protagonist
    Steam97%
    Achieve13
    Deckplatinum
  5. #595% of 46,933 Steam reviews
    FTL: Faster Than Light game key cover art

    FTL: Faster Than Light

    $9.99 -69%
    $3.04
    driffle & 19 stores
    2012
    RoguelikeSpaceStrategy
    Steam95%
    Achieve51
    Deckplatinum
  6. #696% of 24,602 Steam reviews
    Soma game key cover art

    Soma

    $29.99 -81%
    $5.40
    gamivo & 18 stores
    2015
    HorrorPsychological HorrorAtmospheric
    Steam96%
    Achieve10
    Deckplatinum
  7. #795% of 70,430 Steam reviews
    Black Mesa game key cover art

    Black Mesa

    $19.99 -66%
    $6.67
    driffle & 18 stores
    2020
    FPSRemakeAction
    Steam95%
    Achieve50
    Deckgold
  8. #897% of 5,992 Steam reviews
    Supreme Commander: Forged Alliance game key cover art

    Supreme Commander: Forged Alliance

    $12.99 -60%
    $5.19
    indiegala & 16 stores
    2007
    StrategyRTSSci-fi
    Steam97%
    Deckgold
  9. #995% of 17,130 Steam reviews
    The Talos Principle game key cover art

    The Talos Principle

    $29.99 -88%
    $3.40
    driffle & 30 stores
    2014
    PuzzlePhilosophicalFirst-Person
    Steam95%
    Achieve40
    Deckplatinum
  10. #1097% of 3,482 Steam reviews
    Metal Garden game key cover art

    Metal Garden

    $5.99 -32%
    $4.04
    kinguin & 7 stores
    2025
    AtmosphericFPSSci-fi
    Steam97%
    Achieve9
    Deckpending
  11. #1195% of 13,529 Steam reviews
    Half-Life: Opposing Force game key cover art

    Half-Life: Opposing Force

    $4.99
    steam & 3 stores
    1999
    FPSActionClassic
    Steam95%
    Deckplatinum
  12. #1296% of 10,050 Steam reviews
    Star Wars: Republic Commando game key cover art

    Star Wars: Republic Commando

    $9.99 -51%
    $4.82
    driffle & 16 stores
    2005
    FPSActionTactical
    Steam96%
    Deckplatinum
  13. #1397% of 3,856 Steam reviews
    Arctic Eggs game key cover art

    Arctic Eggs

    $9.99 -93%
    $0.68
    k4g & 12 stores
    2024
    CookingSurrealPhysics
    Steam97%
    Achieve16
    Deckplatinum
  14. #1497% of 2,410 Steam reviews
    Primordia game key cover art

    Primordia

    $9.99 -44%
    $5.57
    kinguin & 10 stores
    2012
    Point & ClickAdventurePost-apocalyptic
    Steam97%
    Achieve29
    Deckplatinum
  15. #1597% of 2,484 Steam reviews
    X-COM: UFO Defense game key cover art

    X-COM: UFO Defense

    $4.99 -98%
    $0.09
    GameSeal & 19 stores
    1994
    StrategyClassicTurn-Based Strategy
    Steam97%
    Deckgold
  16. #1696% of 7,278 Steam reviews
    Star Wars: Jedi Knight - Jedi Academy game key cover art

    Star Wars: Jedi Knight - Jedi Academy

    $9.99 -49%
    $5.07
    driffle & 14 stores
    2003
    ActionSci-fiThird Person
    Steam96%
    Deckgold
  17. #1796% of 3,425 Steam reviews
    Defense Grid: The Awakening game key cover art

    Defense Grid: The Awakening

    $9.99 -67%
    $3.29
    loaded & 11 stores
    2008
    Tower DefenseStrategySci-fi
    Steam96%
    Achieve87
    Deckgold
  18. #1896% of 2,549 Steam reviews
    Total Annihilation game key cover art

    Total Annihilation

    $4.99
    steam & 1 store
    1997
    RTSStrategyClassic
    Steam96%
    Deckplatinum
  19. #1994% of 17,961 Steam reviews
    Star Wars: Knights of the Old Republic II - The Sith Lords game key cover art

    Star Wars: Knights of the Old Republic II - The Sith Lords

    $9.99 -76%
    $2.33
    GameSeal & 18 stores
    2005
    RPGStory RichSci-fi
    Steam94%
    Achieve57
    Deckgold
  20. #2096% of 2,533 Steam reviews
    Dystopika game key cover art

    Dystopika

    $6.99
    steam & 1 store
    2024
    CyberpunkSandboxDystopian
    Steam96%
    Achieve15
    Deckgold
  21. #2194% of 8,465 Steam reviews
    The Talos Principle II game key cover art

    The Talos Principle II

    $29.99 -75%
    $7.48
    driffle & 21 stores
    2023
    PuzzleStory RichPhilosophical
    Steam94%
    Achieve87
    Deckgold
  22. #2295% of 5,589 Steam reviews
    Warhammer 40,000: Dawn of War game key cover art

    Warhammer 40,000: Dawn of War

    $14.99 -62%
    $5.60
    kinguin & 36 stores
    2004
    StrategyRTSBase Building
    Steam95%
    Deckplatinum
  23. #2394% of 7,599 Steam reviews
    Cosmoteer: Starship Architect & Commander game key cover art

    Cosmoteer: Starship Architect & Commander

    $19.99 -7%
    $18.49
    gamivo & 6 stores
    2022
    Sci-fiSingleplayerBuilding
    Steam94%
    Deckgold
  24. #2497% of 1,355 Steam reviews
    The Message From Deep Space game key cover art

    The Message From Deep Space

    $9.99
    steam & 1 store
    2026
    SciencePuzzleAliens
    Steam97%
    Achieve33
  25. #2596% of 2,180 Steam reviews
    Vertigo 2 game key cover art

    Vertigo 2

    $29.99 -79%
    $6.16
    driffle & 11 stores
    2023
    VRIndieSci-fi
    Steam96%
    Achieve52
    Deckplatinum
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