Saltline: the Claude Fable 5.2 shooter an Anthropic engineer says took 8 hours

Saltline is a first-person shooter set at a container port at night, and it runs free in the browser as a shared Claude artifact. Felix Rieseberg (@felixrieseberg), who works at Anthropic and co-maintains Electron, posted it on November 9, the day Anthropic released Claude Fable 5.2, with this line: “I wanted to test Fable 5.2’s quality with one-shot prompts without human feedback.”

The title card reads “Port Authority Breach Unit, Saltline Terminal, 05:42.” The port’s security net has gone feral, and your job is to cut its three uplinks and reach the boat. In Felix’s gameplay video you fight through stacked shipping containers with a rifle you can aim down the sights, against four-legged security robots on the docks and drones overhead.

One-shot prompts, 8 hours, about $550

“Everything in this game is from scratch: models, sounds, textures,” he wrote. He puts the cost at about $550 at API prices, for about 2.7 million output tokens and 445 million input tokens, “heavily cached,” and says the run took 8 hours.

The next day Ali Can Meydan (@mahluukat) opened the game’s source and posted that the whole game, the Three.js 3D library included, is one HTML file of 1.42 MB, with no outside game assets: its 3D shapes, textures and sounds are generated in code while it runs. The game’s own title screen says the same thing, that every surface, machine and sound is generated in your browser.

How to play

No download and no sign-up. It’s a shared artifact on claude.ai: the Sign in button at the top is optional, and it loaded for us signed out. The whole game came to about 2.2 MB in our check on November 10. While it builds the port it shows “stacking containers” for a few seconds, then a title screen with Deploy, Settings and Controls. claude.ai labels the page as user-generated content.

The Controls screen lists W A S D to move, the mouse to look, left click to fire, right click to aim, R to reload, E to cut a relay, Space to jump, Shift to sprint, C to crouch and Esc to pause. It also lists touch controls: left thumb to move, right thumb to look, with buttons for fire, aim, reload and jump.

2.9 million views in about a day

About 25 hours after Felix posted it, his post had about 2.9 million views, 11,000 likes and 7,300 bookmarks. Kevin Ngo’s What the water keeps, another Fable 5.2 game posted the same day, had about 413,000 views. On its first full day on NeonGameWall, Saltline was our second most-played game, behind only Teleoperator.