Single-player games like Gray Goo
Below are 8 single-player Steam games similar to Gray Goo, ranked by player overlap. Every pick carries Steam's Single-player category, so multiplayer-only titles or always-online games don't sneak in. imho.run pulls the category data from Steam directly — Single-player here matches what the store labels.
Want the full alternatives list (paid + free + Steam Deck + cheaper picks)? See the parent games like Gray Goo page.
Ranked picks
- 1
UfoPilot : The Phadt Menace - Steam Edition
Single-player alternative to Gray Goo — playable solo, no multiplayer required. Shares Action and Indie with Gray Goo.
A sci-fi retro side-scrolling shoot-em-up / rescue game.
- 2
FORTRESS DEFENDER
Single-player alternative to Gray Goo — playable solo, no multiplayer required. Shares Action and Indie with Gray Goo.
This game, "FORTRESS DEFENDER", is a side-scrolling power-up shooting game with an 80's flavor. Defeat the enemies that appear one after another, dodge their attacks, and aim for the boss that lurks in the depths of the stage. There are a total of eight stages with various tricks and bosses.
- 3
Chromacell
Single-player alternative to Gray Goo — playable solo, no multiplayer required. Shares Action with Gray Goo.
In this sideways scrolling shmup, take control of your spaceship and navigate through vibrant pixelated environments filled with hordes of enemy spacecraft. Upgrade your ship and weapons, dodge enemy fire while blasting through each stage. Emerge victorious as the ultimate space pilot!
- 4
MoonLess
Single-player alternative to Gray Goo — playable solo, no multiplayer required. Shares Action and Indie with Gray Goo.
Moonless is a challenging side-scrolling platformer in the style of classic arcade games of the 1980s, where you control a helpless astronaut who has been left stranded on the moon, and now has to face an invading alien force to earn a chance to go home.
- 5
PigShip and the Giant Wolf
Single-player alternative to Gray Goo — playable solo, no multiplayer required. Shares Action and Indie with Gray Goo.
Pig Ship and the Giant Wolf is a classic Shoot'em Up with a 8btis monochrome aesthetic. Cross the 6 worlds full of enemies and defeat the Giant Wolf to save your brothers.
- 6
Space Warpster
Single-player alternative to Gray Goo — playable solo, no multiplayer required. Shares Action and Indie with Gray Goo.
A fast-paced retro arcade shooter inspired by classic 1980s side-scrolling space combat. Weave through organic obstacles, survive relentless enemy waves, and defeat powerful end-level bosses in a pure, skill-driven singleplayer experience.
- 7
Super Arcade Boy in Defender of Planet Earth
Single-player alternative to Gray Goo — playable solo, no multiplayer required. Shares Action and Indie with Gray Goo.
A retro-style classic side-scrolling shoot ’em up. Fly Super Arcade Boy through 8 levels, blast enemy waves, grab power-ups, and take down bosses.
- 8
Earthion
Single-player alternative to Gray Goo — playable solo, no multiplayer required. Shares Action with Gray Goo.
Earthion is a side-scrolling space shooter developed natively for 16-bit systems. Guide space fighter pilot Azusa Takanashi in her fight to repel the alien invaders and save planet Earth.