claude fable 5 is live. spawn 5.0 was built with it: 1,687 prompts, 102 sessions, my job shifted from architecture to judging taste.
what we built, each of which would've been at least a month with a whole team on opus:
— a from-scratch physics engine (mantle) that rivals rapier, testable in a day as a side thread
— clustered froxel lighting: 8 lights to 1,000 fully dynamic ("it's stupid fast" — creator of threejs)
— realtime diffuse GI on webgpu, on your phone (landing in the next update)
— million-particle gpu vfx with a shader architecture beyond what unreal and unity ship
— mmo-scale netcode
plus, for good measure: an (alpha) native ios app.
all of it in about a week. all of it running on mobile. and the list doesn't include half of what we shipped — full changelog in the thread below.
and the part the benchmarks won't show you: this model has a wonderful personality. it's genuinely funny. i laughed so hard i cried multiple times, mid-physics-rewrite. the genius and the character aren't separate features.