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Purrl: a haunted co-host for live shopping
Purrl is my new co-host when I sell live on Whatnot. For Halloween, she’s a 3D ghost-cat who answers buyers’ questions, calls out bids and celebrates every sale. For Halloween she’s wearing her favorite outfit: a sheet.
The chat drives the show. Raids bring swarms of bats, new followers rise from the pumpkin as named ghosts, and viewers vote trick or treat over a bubbling cauldron. A treat pours candy into the pumpkin; a trick gets her a little possessed.
How it’s built
Built with the Rive CLI and GPU Canvas. The scene is written in Rive Markup Language (RML), with Luau scripting, data binding and state machines: six artboards, a 131-property view model, and keyboard and pointer interaction. It was built and checked with the Rive CLI by a coding agent, then pushed to the Rive Editor.
Everything spooky is custom WGSL on GPU Canvas: six shaders of our own, for instance: 3D bats, name ghosts, cauldron liquid, candy that piles up in the pumpkin, and one composite pass for the storm, fog, glitch and possession. They run on top of a custom Rive 3d engine’s physically based renderer.
On stream, the same Rive file runs as a 9:16 overlay in OBS. It stays clear of Whatnot’s chat, buttons and pinned product, and it reacts to events from the show in real time, with her voice lip-synced live.
About the live link
Purrl is built to run inside a real Whatnot stream, where follows, bids, sales, raids and chat votes arrive as events from the show. The public page can’t connect to a live stream, so it plays a scripted demo show that fires similar events on a 2½-minute loop. You can also play with her directly: move the cursor and she follows it, click her head to pet her, drag to orbit the camera, flip the storm switch, or click the page and press X for lightning, J for a jump scare, or 1–8 for expressions.
Features used: Rive CLI · GPU Canvas (WGSL) · Scripting (Luau) · Data Binding · State Machines
The rooms in the video are painted with an image model. Purrl, her show and every screen in it are real Rive renders and recordings.
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Start halloween already. 🎃
My entry for the Rive Halloween Challenge is a jack-o-lantern with no mesh and no textures. Every pixel is a ray marched signed distance field in a WGSL shader running on Rive's GPU Canvas. There's a candle inside that bleeds through the rind, and fog drifts around him under a bloom pass.
His head follows your cursor on a spring. Move toward the Start button and his mouth opens, his brows drop, the violins swell and the screen starts to shake. Click it and the candle goes red, green, orange, the rim lights spin, and he dances and twirls to a disco loop I generated in Python.
How I built it:
• I wrote the scene in RML with the Rive CLI and a coding agent
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• Around 50 view model properties are data bound (face shape, lights, fog, bloom)
• State machines handle the button states and party mode
• I tuned the colors, lighting and mood by hand in the Rive Editor
The table is haunted, so is the cue ball!
For the @Rive Halloween Challenge here on Contra, I've channeled my inner demons to create a spooky 8-ball pool game called 'Ghoul Table'. 🎱
It was built entirely in Rive using the new CLI, 3D objects, shaders, physics and more... and it ships as a .riv file under 10MB!
What crazy cue ball should I add to the game next? I'll implement the best suggestions!
Delivery vs Zombies is my entry for the Rive Halloween Challenge with Contra. 🧟🍕
A one-level runner set in Buenos Aires on a full-moon night: Matilda has to deliver a pizza through a city full of zombies, with werewolves howling from the rooftops and fog rolling in, for an app that never stops rushing her. At the end, the app prints your receipt, with deductions.
Made from scratch over nine days for this challenge:
Rive CLI: the whole file written in RML from the terminal with Claude Code. 291 commits, checking every change with headless screenshots and pushing back and forth with the Editor.
GPU Canvas: a custom WGSL shader for film grain, chromatic aberration and lens blur, tuned to hold 60 fps.
Scripting for the game loop and physics, Data Binding to dress every zombie at random, State Machines for characters and UI.
The agent was fast, but its art came out generic. So it blocked out the shapes, and I redrew, rigged and animated everything by hand in the Rive Editor, adapting Vero Beltrán's original characters so they read from far away. Matilda squashes on every landing, the zombie bite runs 52 frames, your scooter parts stay where you got caught, and the receipt prints line by line. The UI comes from a design system I built in Claude Design. Original chiptune music.
Playtested with friends until the jumps felt right. English and Spanish, effects and audio can be switched on and off while you play. Desktop only for now.
Let me know if you make the delivery on time. 😅