Onceval
Press kit

Onceval, in words and pictures.

Everything you need to write about Onceval or share it: descriptions, facts, logos, key art, screenshots, the trailers, a recorded ChatGPT session and our social accounts.

Download the press kit hello@onceval.com

One ZIP (2.9 MB): every image below, at full size, and a text file with the descriptions and facts.

Onceval key art: an open storybook under the northern lights, a lit tower on an island rising from its pages, Nessie in the loch, and a magician's hand placing a tree. Text: Onceval. Create little worlds. Tell stories. Step inside.
About

Onceval in three lengths

One line

Onceval turns a few sentences to ChatGPT or Claude into a little 3D world with a story you can play and share.

Short (50 words)

Onceval makes small playable worlds from a description. Tell ChatGPT or Claude about a place and something that happened there; Onceval builds the island, its lights, secrets and lost souls, checks the story can be finished, and gives you a link anyone can play in a browser.

Long (120 words)

Onceval makes small playable worlds from a description. You describe a place and something that happened there to your AI assistant, ChatGPT or Claude. The assistant writes an island and a story; Onceval compiles them into a 3D island with buildings, lights, secrets and lost souls, checks that the story can be played to its end, and shows it beside the chat. Change your mind and ask for a ruined chapel or a moved lighthouse: the island is rebuilt. Anyone can play the finished tale in a web browser, without an account. Onceval calls no AI model of its own: the assistant writes, Onceval builds, checks, stores and renders. It launched in October 2026 with a Halloween tale, Samhain on Eilean Dubh.

Facts

Fact sheet

Name
Onceval
Tagline
Create little worlds. Tell stories. Step inside.
What it is
Little 3D worlds with a story, made by describing them to an AI assistant, played in the browser.
Made by
Mik Bry, MDB (MARABOT) SAS, France
Launched
October 2026, Halloween Special Edition
Create with
ChatGPT or Claude, by connecting Onceval (an MCP connector)
Play on
A web browser with WebGPU: current Chrome, Edge or Safari. No account needed to play.
Price
Free to play. Creating: a free plan to start, and the Halloween pack, €4.99 once (VAT included).
Featured tale
Samhain on Eilean Dubh: wake a haunted Hebridean island's lights and lead its lost souls home before dawn.
Website
onceval.com
Contact
hello@onceval.com
Follow

Onceval on social media

Social kit

Avatar and banners, at each platform's size

One avatar everywhere: the faceless magician, as on YouTube. Dashed lines show where each platform places the round avatar or keeps the banner visible on every screen.

Onceval's avatar: the faceless magician, two pale eyes in a purple hood with gold trim and a four-point star.

Avatar, all platforms

Square, shown in a circle. YouTube 800×800 · X 400×400 · Bluesky 1000×1000 · Instagram 320×320 or more · TikTok 200×200 or more. Upload the 1024 or 800 version anywhere.

1024×1024 PNG800×800 JPG400×400 JPG

YouTube

Banner 2560×1440, under 6 MB. Only the centre 1546×423 shows on every device; the box marks it.

Banner 2560×1440

X

Header 1500×500. The avatar covers the bottom left, so the art sits to the right of it.

Header 1500×500

Bluesky

Banner 3000×1000, same layout as X (the avatar sits at the bottom left).

Banner 3000×1000

Instagram and TikTok

No banner: the avatar only. For posts and videos, use the key art, the screenshots and the vertical trailer below.

Avatar 1024×1024Vertical trailer (9:16, with sound)Vertical poster 720×1280
Art

Key art and screenshots

Onceval key art with the title and tagline.
Key art, with title · 2112×744
The storybook artwork without text: an island rising from an open book under the northern lights.
Storybook art, wide · 2560×1240
Onceval's link preview card.
Share card · 1200×630
Eilean Dubh at night: a stone tower and a trail of golden lanterns down to the loch.
Eilean Dubh at night · 1280×720
The tower's hall, where the laird's chair is empty.
The hall · 1280×720
A cold hearth waiting to be lit.
The hearth · 1280×720
The ferryman's boat crossing the loch.
The crossing · 1280×720
White heather on the island.
White heather · 1100×880
The open storybook, close up.
Storybook, close up · 1200×627

The Halloween pack

A haunted island built with the Halloween pack.
Haunted island · 1200×789
A haunted kirk with corpse lights.
Haunted kirk · 1200×789
Carved neep lanterns.
Neep lanterns · 1200×789
The witch's cauldron.
Cauldron · 1200×789
Video

The two trailers

Both with sound, in full HD. Play them here or download them.

The trailer · 16:9 · 1:13

The full trailer. For YouTube, websites and articles.

MP4 1920×1080, with sound (25 MB)Poster 1280×720Light, silent 720p

The vertical cut · 9:16 · 0:36

For TikTok, Instagram Reels and YouTube Shorts.

MP4 1080×1920, with sound (14 MB)Poster 720×1280Light, silent 720p
In ChatGPT

A real session, start to finish

Recorded in ChatGPT on 22 October 2026: a tale described in the chat, built and checked by Onceval, changed on request, then played beside the chat.

Onceval in ChatGPT · 2:13

Dream a tale, play it beside the chat. Captioned, no sound.

MP4 1920×1080 (14 MB)Poster 1280×720

Create and play · 0:52

The short loop: ask, build, fix, play to the ending. For articles, READMEs and posts.

GIF 1505×812 (18 MB)MP4 loop (2 MB)
Brand

Marks, colours and type

The magician mark

The faceless magician, used for the site's icon. Vector, any size.

Onceval's mark: a faceless magician in a purple hood with a gold star.
SVG

The souls of Samhain

Portraits of the Halloween tale's characters (SVG).

Mairi, the cookIain, the fishermanBrother Fionn, the monkThe lost soldierThe ferryman

Colours

Night#0B1219
Lime wash#F4EAD5
Lantern gold#E9BC77
Magician purple#4B3073

Type

Fraunces for titles and the name. Figtree for text. Both are free (SIL Open Font License) on Google Fonts.

The name

Write Onceval, one word, capital O. The four-point star ✧ may stand before it.

Use

Using these files

You may use the files on this page to write about Onceval, review it, or share it. Please don't change the art or the mark, and credit "Onceval" when you show them. For anything else, or a question, an interview or a custom asset, write to hello@onceval.com.