Tree Appreciator
Simon Willison’s Weblog Simon Willison
Claude built a Tree Appreciator game from a prompt about comparing two trees. It took 3 hours and 7 minutes, and somehow ended up genuinely fun.
Based on reporting by Simon Willison’s Weblog, Simon Willison — read the original for the full story.
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Simon Willison tried another game experiment with Claude, this time in the default Claude iPhone app rather than Claude Code mode. The prompt was simple on paper: build a three.js game called Tree Appreciator, show two algorithmically generated trees, and make the whole thing about noticing the differences between them.
He also asked Claude Opus 5.5 Max to think hard about making it fun and beautiful. That sounds like the sort of instruction people give to language models when they’re trying not to sound too vague. Here, though, it appears to have worked a little too well.
Claude spent 3 hours and 7 minutes on the job, then came back with a cosy spot-the-difference game. It includes music, animation, and achievements, and Willison says it is quite compelling to play.
The slightly awkward twist is that this was a live example of the thing he’d recently talked about: telling Opus to make something fun actually seems to matter. The result is not just a demo that exists. It is a polished little game about appreciating trees, which is a very specific kind of absurdity and also, apparently, a working design brief.
My take — AI-written commentary, not fact-checked reporting
This is the sort of AI output that matters more than the grand pronouncements. Not because it’s revolutionary, but because it shows how far a blunt creative prompt can go when the model is willing to sit there and grind for hours. The industry loves to brag about speed; sometimes the real trick is getting something charming instead of something merely fast.
Read more about this at: Simon Willison’s Weblog
