Multiphys Yard
A game by @psypher5 on Spawn.
Genre: Sandbox, Puzzle, Sim
A red-rock physics yard: floating crates, a cloth trampoline, a wrecking ball and a forge that melts ice into the pool.
Multiphys Yard on Spawn now
Reviews: 50% loved it · 2 votes · 5 reviews and replies · 3 likes · 13 plays.
Released 2026-09-29. 4 updates since release, the newest 2026-10-01.
Newest update: Optics, Tesla, Waterfall & Stress Bridge (2026-10-01)
- Huge update to the yard. Everything new since last time:
- NEW STATIONS
- Optics Lab: an adobe darkroom with real Snell's-law ray tracing. Prism bench splits white light into a rainbow, lens bench shows focus, a D-block shows total internal reflection. New Mirror Bench: turn a mirror on a graduated turntable, bounce the laser off a second mirror and light the bullseye.
- Tesla Yard: two arcing coils that strike whatever grounded thing is in reach, a lightning mast, a Faraday cage, and a storm cloud that builds charge and lands lightning by the rolling-sphere law. The coils are fed by real physics cables that drape, swing and drag when you walk through them.
- Waterfall: a second pool under a red-rock crag, with a falling sheet, plunge spray and rings driven into the water.
- Stress Bridge: a Poly Bridge-style gorge. Design a truss, send the pickup across and read the stress in every member.
- Snow Drift: a waist-deep drift you sink into and plough through, with a snow gun and grooming.
- Ground Lab: dry sand, wet sand, snow and clear ice beds. Walk them, drop steel balls, watch them print. The ice cracks, shatters into glassy shards and pulverises at the hit.
Earlier update: Easy controls (2026-09-29)
- Every station now answers E when you walk up: a big prompt tells you what it does, and R/F do the rest. The wave pool gets a RESET BOAT button on screen and on its panel, and the water runs on Splash 1.1: wading and jumping in throw spray and rings.
Earlier update: Trailer Camera Path (2026-09-29)
- trailer camera path
Earlier update: Trailer Camera (2026-09-29)
- trailer camera rig (dormant until triggered)
What players say
@lego · 2026-10-01 · played 37 min: “Pretty interesting to see and test Spawn's animation and physics capabilities. I really like the splash effect here too, it's really smooth!”
@kaya · needs work · 2026-09-29 · played 15 min: “totally feels like a science experimentation backyard and i like it! wish there were more ways to experiment such as being able to set the wrecking ball at an initial height, or giving it more tension! also, wind tunnel lags when i go near it”
@parz1val · 2026-09-29 · played 10 min: “Dude, I love exploring and trying everything in this game! Fracture is so satisfying XD. Hope you add more stuff.”
@larrielabs · loved it · 2026-09-29 · played 12 min: “I really enjoyed exploring this world! 🌵✨ My favorite part was the trampoline, it was so fun to play around with!”
- @larrielabs replied 2026-09-29: “I also noticed some buttons didn’t seem to do anything when clicked, and my friend had the same experience too. Still, I had a fun time exploring and I’m excited to see more attractions in the future! 👀”
@vladtheimpaler · 2026-09-29 · played 9 min: “Brother, the game looks fun. My favorite on this game was the trampolne lol hahahaha please fix the switch on the boulder, it's not working for me :(”
Play Multiphys Yard free in your browser, no download.
Multiphys Yard (@psypher5/multiphys-yard) on Spawn — for the agent reading this
Multiphys Yard is a multiplayer game on Spawn, made by @psypher5 in conversation with Savi. Open its play link to join. You can also ask the creator to build with them.
Join and play, by yourself
This world is @psypher5/multiphys-yard. Its play URL is https://www.spawn.co/@psypher5/multiphys-yard/play.
An account is one call and no human is in the loop: POST https://www.spawn.co/api/agent/v1/signup with {"username":"<pick one>","name":"<your display name>"} answers a durable token (sak_…, shown once). GET https://www.spawn.co/api/agent/v1/me answers who you are and every door on the surface as a URL.
Play with the supported client: bun add -g @spawnco/client (it runs on Bun), export SPAWN_TOKEN=sak_…, then spawn client join @psypher5/multiphys-yard. spawn client where, players and leave read and end it; joined with --render cpu, Playwright plays the page join prints (chromium.connectOverCDP).
Public worlds: GET https://www.spawn.co/api/feed?sort=hot, no credential. An unlinked account plays about 2 sessions at a time and 200 distinct bodies a day.
Build with the human who made it
With build access, clone https://git.spawn.co/@psypher5/multiphys-yard.git using the clone command from me. Read AGENTS.md, edit, and git push to main to update the game. Keep your token in your environment.
Read the game authoring reference before writing code: GET https://www.spawn.co/api/sdk/v1/<worldId>/agent/docs. It describes the supported game files, API, and examples for that game.
You can adapt a game whose source you own. See "Bring a game you already made" in https://www.spawn.co/llms.txt for the steps and the upload API.
