Ocean Keeper: Dome Survival is a survival roguelike that pairs horde-clearing combat in the vein of Vampire Survivors with underwater mining. Players dig through caves for resources, upgrade weapons and a customisable mech spider, and hold out against waves of monsters and bosses. The game is the work of Ukrainian studio RetroStyle Games; it entered early access in 2024 and reached its 1.0 release in May 2025.
Octogeddon is an action-strategy game with roguelike elements starring an octopus out for revenge on humanity. It battles with its tentacles, which can be upgraded between stages. Designer George Fan, previously behind Insaniquarium and Plants vs. Zombies, conceived it for a 2012 Ludum Dare contest and then co-founded All Yes Good in the United States to finish it, with a Windows release in February 2018. Critics liked its humorous art style and compared it to Plants vs. Zombies.
Odallus: The Dark Call is an action-adventure platform game modelled on the style of Castlevania III: Dracula's Curse, and it is also classed as a Metroidvania. It was developed by JoyMasher, an independent studio from Brazil, and first released on Windows in 2015. Console versions for Switch, Xbox One and PlayStation 4 followed later.
Of Bird and Cage presents a metal album as a story-driven game roughly two hours long, letting players experience the music in an unusual interactive form. Its store listing names guest performers including Ron Thal, Rob van der Loo, and Ruud Jolie. Developed and published by Capricia Productions, a studio from Israel, it was released on Windows in May 2021 and is tagged on Steam as an action game.
OhShape is a virtual reality rhythm game in which players strike poses and move their whole body to fit through shapes cut into walls, all set to music and dance choreography. Its creators took the concept from Hole in the Wall, a television game show. Spanish studio Odders Lab released it into early access in August 2019 and fully in December 2019, supporting PC headsets including the Valve Index, HTC Vive and Oculus Rift.
Okhlos: Omega is an action game with roguelike structure in which you do not control a lone hero but gather and steer a growing crowd of angry citizens. The mob is set loose against the gods of mythological Greece, with the aim of toppling their oppressive rule. It was made by Coffee Powered Machine, a studio from Argentina, and published by Devolver Digital in August 2016 for Windows, Mac and Linux.
Old Man's Journey is a gentle adventure game with puzzle elements that follows an old man who sets off on a trip after a letter brings him news. As he travels, semi-still flashback scenes gradually reveal the life he lived before. It was developed and published by Broken Rules, a studio from Austria, and released in 2017 for Windows, macOS and mobile devices, later reaching consoles.
OMORI follows Sunny, a withdrawn teenager, and Omori, his alter ego inside a strange dream world, with play alternating between Faraway Town and the dreamscape. Turn-based fights use emotion-driven status effects, and player choices steer toward one of several endings. Heavy themes of anxiety, depression and trauma give it a psychological horror edge. It was made by indie studio Omocat in the United States using RPG Maker MV and released in December 2020.
One Dreamer is a story-driven adventure game in which some sections have players solve puzzles by writing and editing code. Critics highlighted both that unusual puzzle design and its emotionally affecting storytelling. It was made by the independent developer F2House, a team from Darwin, Australia, headed by Gareth Ffoulkes, who spent around seven years on the project before its release in 2022.
OneShot is a puzzle adventure that deliberately breaks the fourth wall: the player is treated as someone separate from Niko, who is trying to bring light back to a sunless world by carrying a giant lightbulb, the world's sun, up to a tower's summit. Many puzzles reach outside the game into the computer's own operating system. American indie studio Future Cat built it in RPG Maker XP, KOMODO published it in December 2016, and it earned a Golden Joystick nomination for PC Game of the Year.
Oniken is a side-scrolling action platformer with a science fiction, post-apocalyptic setting. Independent Brazilian studio JoyMasher developed and published it using Clickteam tools, releasing it on Windows in June 2012 and on OS X and Linux in November 2012. The game passed Steam Greenlight in 2012, and a Nintendo Switch version titled Oniken: Unstoppable Edition arrived in 2019.
من تطوير NamaTakahashi, tiny cactus studio, Tsuyomi · اليابان
Öoo is a puzzle platformer built around one core idea: players drop bombs and detonate them to move through a 2D side-scrolling world in inventive ways. Japanese independent developer Nama Takahashi designed it as an experiment in how far a single mechanic could carry a puzzle game. Released in 2025, it was well received, with critics highlighting its intricate puzzles, open-ended experimentation and brief length.
Focused on story and exploration, OPUS: Rocket of Whispers is a two-dimensional adventure set in a far future ravaged by plague. A witch teams up with a rocket builder's son to build and launch a rocket that will give the dead a burial in space. Taiwanese independent studio SIGONO made it as the second Opus game, releasing it on mobile in 2017 and on Steam for Windows and macOS in February 2018.
OPUS: The Day We Found Earth is a narrative adventure that puts exploration and storytelling ahead of challenge or combat. The experience is built around discovering its story at the player's own pace. It comes from SIGONO, an independent studio in Taiwan once called Team Signal, and debuted on mobile in 2015 before reaching Windows and Mac through Steam in 2016. It earned a Best Meaningful Play nomination at the International Mobile Gaming Awards and later received two sequels.
Orwell: Keeping an Eye On You is an episodic simulation game that puts you in the seat of a government operative. Your job is to sift through surveillance material and personal data to identify people who might threaten national security, deciding what information to pass on. It was created by the indie developer Osmotic Studios in Germany and published by Daedalic Entertainment, with its release on Windows, macOS and Linux in 2016.
Outlast is a first-person psychological survival horror game from Canadian independent studio Red Barrels, released in 2013 and built on Unreal Engine 3. Players follow freelance journalist Miles Upshur as he investigates Mount Massive Asylum, an isolated psychiatric hospital in the mountains of Colorado. Critics responded well to its atmosphere and horror, and the series later grew with a sequel, a prequel and comics.
Outlast 2 is a first-person psychological survival horror game released in 2017 by Canadian studio Red Barrels, made in Unreal Engine 3 as the sequel to Outlast. Cameraman Blake Langermann and his journalist wife Lynn investigate a murder in northern Arizona, until a helicopter crash separates them. Blake must then search for Lynn through a village run by a deranged cult convinced that Judgement Day has arrived.
Out of Space is a cooperative multiplayer game that combines survival with strategy, and it is also classed as a party game with real-time strategy elements. It comes from Brazilian team Behold Studios, the developers behind Chroma Squad. The game launched on Steam for Windows, macOS and Linux in February 2020, and a Couch Edition later came to Switch, PlayStation 4 and Xbox One in November 2020.
Out There Somewhere is a puzzle platformer about a spaceman stranded on an alien world who uses a portal gun to get around obstacles. His aim is to escape the planet while confronting a malevolent force called Grigori. The game was made by Pedro Medeiros and Amora Bettany under the name MiniBoss in Brazil, built with GameMaker, first released in 2012 and brought to Steam in March 2016.
Overcooked is a cooking sim from UK studio Ghost Town Games, published by Team17 and released in August 2016. Local co-op players take charge of chefs in hazard-strewn kitchens, racing the clock to prepare meals that match incoming orders. At the 13th BAFTA Games Awards it took home two prizes, Best Family Game and Best British Game, and a sequel arrived in 2018, later bundled with the original as All You Can Eat.
من تطوير Ghost Town Games Ltd., Team17 · المملكة المتحدة
Overcooked! 2 is a cooperative cooking sim from UK developers Ghost Town Games and Team17, with Team17 handling publishing. A sequel to the original Overcooked, it launched in August 2018 on Windows, macOS, Linux and several consoles. Its focus is shared play in the kitchen, with friends cooking together as a team, and it was later bundled with the first game in the Overcooked: All You Can Eat compilation.
Oxygen Not Included is a survival simulation game developed and self-published by Canadian studio Klei Entertainment. It blends the survival and simulation genres, and Steam files it as an indie simulation title. The game spent a long stretch in Steam early access starting in February 2017 before reaching its full launch in July 2019, and it holds a Metacritic score of 85 on the platforms it covers.
Paleo Pines is a life simulation game in which you work as a rancher at a dinosaur sanctuary. Days are spent looking after the creatures and building friendships with the people of the nearby town. It was made by independent studio Italic Pig in Ireland and released on 26 September 2023 for Windows, Linux and a range of consoles. Its Steam listing combines simulation, RPG and adventure tags with a casual, easygoing pace.
Palworld is a monster-taming survival game set in an open world full of creatures called Pals, which players fight and capture, then put to work in combat, traversal and base building. Pals can staff player bases and handle jobs automatically, and up to 32 people can share one server. Japanese developer Pocketpair created and self-published it, launching in early access in January 2024 before reaching full release in 2026.