It's not easy to search the marketplace for GM-less games, so here is a list of games I've found. Several of the games have links to reviews & gameplay videos on the marketplace pages.

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Alice is Missing

Alice is Missing^(Market)

Game is for 3-5 players, and is designed to be exactly 90 minutes.

Alice is Missing, is a silent role-playing game about the disappearance of Alice Briarwood, a high school junior in the small town of Silent Falls.

This immersive, mystery RPG is played without verbal communication. Players inhabit their character for the entirety of the 90-minute play session, and instead of speaking, send text messages back and forth to the other characters in a group chat, as well as individually, as though they aren’t in the same place together.

Companion's Tale

Companion's Tale^(Market)

Game is for 3-4 players and takes approximately 2 ½ hours to play.

Companions’ Tale is a map-making storytelling game where you tell the tale of an epic hero, righting wrongs and saving kingdoms.

BFF! Best Friends Forever

BFF! Best Friends Forever^(Market)

Best Friends Forever is a tabletop role playing game for 2-6 players of all ages. In it we tell a story about a group of young friends hanging out, having adventures, and exploring how our friendships change and grow.

Dialect

Dialect^(Market)

Dialect is a game about an isolated community, their language, and what it means for that language to be lost. In this game, you’ll tell the story of the Isolation by building their language. New words will come from the fundamental aspects of the community: who they are, what they believe in, and how they respond to a changing world.

Players take away both the story they’ve told and the dialect they’ve built together. Includes a module of complete game setup including a deck of language generating cards used to play the game, and all the rules and backdrops searchable in the in-app and web compendium.

Fall of Magic

Fall of Magic(HD Edition)^(Market)

2-4 Players , 2 or more hours, No GM Required

Magic is dying, and the Magus is dying with it. We travel together to the realm of Umbra where magic was born.

Fall of Magic is a collaborative storytelling game where we play a group of travelers in the company of the Magus. On the way, we’ll encounter strange hosts, fantastic places, and perilous choices as we play to discover who our characters are, how they relate, and how our journey changes them.

A single session will feel like several chapters of a book or a good first episode of a fantasy series. In several sessions you can create a your own epic tale.

Fiasco

Fiasco Complete Bundle^(Market)
Fiasco Core Game^(Market) + 3 expansions

Fiasco is an award-winning story-telling game inspired by cinematic tales of small-time capers gone disastrously wrong.

You’ll tell a story about ordinary people with powerful ambition and poor impulse control!

Lives and reputations will be lost, painful wisdom will be gained, and if you are really lucky, you just might end up back where you started.

You probably won’t be lucky.

For the Queen

For the Queen^(Market)

For the Queen is a card-based story-building game that you and up to five other players can begin playing in minutes. Choose your queen from among fourteen gorgeously varied illustrations—or start from scratch—and use the prompt cards to collaboratively tell a story of love, betrayal, doubt, and devotion.

Number of players: 2-6 Age of players: 13+ Length: 30-120 minutes

The Quiet Year

The Quiet Year^(Market)

For 2 to 4 players one of whom also acts as the facilitator. Games should last from 2 to 4 hours.

The Quiet Year is a map game. You define the struggles of a post-apocalyptic community, and attempt to build something good within their quiet year. Every decision and every action is set against a backdrop of dwindling time and rising concern.

The game is played using a deck of cards – each of the 52 cards corresponds to a week during the quiet year. Each card triggers certain events – bringing bad news, good omens, project delays and sudden changes in luck. At the end of the quiet year, the Frost Shepherds will come, ending the game.

Spoken Magic

Spoken Magic^(Market)

Spoken Magic is a prompt-based collaborative storytelling game for one to four players. The game guides you on a journey through magical lands where you will encounter strange dilemmas that can only be solved through magic— a process that has players sharing their words of power to craft a spell appropriate for the task. Throughout this journey you will investigate the purpose of magic, explore the conflicting desires for safety and heroism, and learn the true nature of your very own magic words.

The Roll20 Edition of Spoken Magic comes with all four decks preloaded, a playmat optimized for the virtual tabletop, and rules adapted specifically to make it easy to play online and translate the magical in-person experience to a digital space.

Travelogue

Travelogue^(Market)

For 1-4 players. 90-120 minutes standard playtime.

Travelogue is a drawing and collaborative world building game about travel. Build worlds together, region by region, and give them life by creating maps, brochures, and postcards of those places. Gameplay involves conversation, dice rolling, writing, and drawing. Play together at the table or asynchronously across the world. Draw with friends of all ages on Roll20 and discover new places, together.