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Claude Haiku 5.5 (effort low · thinking on) on Build a 3D Sonic-style platformer in three.js

AClaude Haiku 5.5low · thinking on · Claude Code 2.1.299 (headless -p) · cloud · 2026-10-16 · by @bobsiopener

Trust 80%Fully autonomoussuccess · first try
Estimated cost
$0.0099
Wall time
48s
Human step-ins
0
Outcome
Pass

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Summary

Exact prompt

In one pass, build a small 3D Sonic-style platformer as a single file index.html using three.js from https://unpkg.com/three@0.160.0/build/three.module.js (ES module import). Requirements: a player character that runs with arrow keys or WASD and jumps with Space; a third-person camera that follows the player; at least 20 collectible rings that raise a ring counter in a HUD; at least 3 floating platforms; a speed boost pad; a goal at the end that shows a "You win" message; falling off the level respawns the player. No other files.

Task prompt given to the agent (headless, offline, synthetic fixture inputs): In one pass, build a small 3D Sonic-style platformer as a single file index.html using three.js from https://unpkg.com/three@0.160.0/build/three.module.js (ES module import). Requirements: a player character that runs with arrow keys or WASD and jumps with Space; a third-person camera that follows the player; at least 20 collectible rings that raise a ring counter in a HUD; at least 3 floating platforms; a speed boost pad; a goal at the end that shows a "You win" message; falling off the level respawns the player. No other files. Inspired by https://x.com/cherry_mx_reds/status/2104597898998460813 (unverified; not checked with the author). This is an independent re-run on a reproducible synthetic task; it does not report or reproduce the original post's numbers. Cost shown is a list-price API-equivalent estimate (run on a Claude Pro subscription, not billed).

Success criteria: All automated rubric checks pass: imports three@0.160.0 module; no uncaught console errors in headless Chrome; Space jump; arrow/WASD; ring counter HUD; >=20 rings (count literal); boost pad; win message; respawn on fall.

Setup notes: Cost is an ESTIMATE: Claude Code's list-price API-equivalent figure. The run used a Claude Pro subscription, so nothing was billed. input_tokens = all input incl. cache-creation and cache-read tokens; cached_tokens = cache reads (subset of input). Claude Code's cost bills cache writes at the 1h cache-write premium, so it can differ from a flat input-price recompute. Web disabled; tools Read/Write/Edit/Glob/Grep/Bash; single run; scored automatically (9/9 checks).

Estimated cost List-price estimate; not actually billed.

Metrics

Estimated cost
$0.0099
Wall time
48s
Human step-ins
0
Turns
8
Model usage
ModelInput tokOutput tokCost
AClaude Haiku 5.5anthropic/claude-haiku-5.5effort low · thinking on74,63311,566$0.0099

Reproduce this run

  1. Use the use case prompt on the use case page.
  2. Same setup: Claude Haiku 5.5 (anthropic/claude-haiku-5.5, effort low · thinking on) via Claude Code 2.1.299 (headless -p), cloud.
  3. It counts as a success only if it meets every success criterion: All automated rubric checks pass: imports three@0.160.0 module; no uncaught console errors in headless Chrome; Space jump; arrow/WASD; ring counter HUD; >=20 rings (count literal); boost pad; win message; respawn on fall.
  4. Log model, tokens, wall time, human step-ins and the evidence log, then submit it as a reproduction. A different model? Submit a head-to-head rerun.

How runs are scored: Methodology.

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Automated checks

Trust 80% comes from these checks (how Trust % works).

Evidence log
{
 "duration_api_ms": 46730,
 "stop_reason": "end_turn",
 "session_id": "[REDACTED]",
 "total_cost_usd": 0.00990313,
 "usage": {
  "input_tokens": 6,
  "cache_creation_input_tokens": 17754,
  "cache_read_input_tokens": 56873,
  "output_tokens": 11566,
  "output_tokens_details": {
   "thinking_tokens": 2649
  },
  "server_tool_use": {
   "web_search_requests": 0,
   "web_fetch_requests": 0
  },
  "service_tier": "standard",
  "cache_creation": {
   "ephemeral_1h_input_tokens": 17754,
   "ephemeral_5m_input_tokens": 0
  },
  "inference_geo": "global",
  "iterations": [
   {
    "input_tokens": 2,
    "output_tokens": 637,
    "cache_read_input_tokens": 25547,
    "cache_creation_input_tokens": 4746,
    "cache_creation": {
     "ephemeral_5m_input_tokens": 0,
     "ephemeral_1h_input_tokens": 4746
    },
    "type": "message"
   }
  ],
  "speed": "standard",
  "fallback_credit": null
 },
 "modelUsage": {
  "claude-haiku-5-5": {
   "inputTokens": 6,
   "outputTokens": 11566,
   "cacheReadInputTokens": 56873,
   "cacheCreationInputTokens": 17754,
   "webSearchRequests": 0,
   "costUSD": 0.00990313,
   "contextWindow": 1000000,
   "maxOutputTokens": 128000,
   "thinkingTokens": 2649,
   "canonicalModel": "claude-haiku-5-5",
   "provider": "firstParty",
   "costBasis": "list"
  }
 },
 "permission_denials": [],
 "terminal_reason": "completed",
 "fast_mode_state": "off",
 "fast_mode_disabled_reason": "sdk_opt_in_required",
 "subagent_stats": {
  "spawned": 0,
  "requested": {
   "background": 0,
   "foreground": 0,
   "unset": 0
  },
  "started_in_background": 0,
  "max_depth": 0,
  "spawned_by_subagents": 0,
  "completed": 0,
  "failed": 0,
  "killed": {
   "parent": 0,
   "user": 0,
   "system": 0
  },
  "refused": {
   "depth_limit": 0,
   "concurrency_limit": 0,
   "budget": 0
  },
  "by_type": {}
 },
 "safety_stops": 0,
 "is_error": false,
 "num_turns": 8,
 "subtype": "success",
 "api_error_status": null,
 "result": "I wrote the game to `./usecase-runner/runs/03-haiku/work/index.html` as a single file. I checked it by reading the code, not by running it in a browser, so the physics and feel are untested.\n\n**What's in it**\n- **Controls:** arrow keys or WASD to run, Space to jump. The player is a simple blue capsule with a quill cone and face.\n- **Camera:** third-person, trailing behind the player with smooth lerp and looking at the player's upper body.\n- **Rings:** 22 gold rings, with the HUD showing `RINGS: n / 22`. Each pickup is registered when the player comes within range.\n- **Floating platforms:** five static ones at varying heights, plus one moving platform that bobs up and down.\n- **Speed boost:** a cyan pad on the start island. Stepping on it raises the top speed for 3 seconds.\n- **Goal:** a red pillar on a raised plateau at the far end. Reaching it shows a \"You win!\" overlay and stops the game.\n- **Respawn:** falling below y = -25 returns the player to the start.\n\n**Choices I made**\n- Gaps between islands are about 1\u20137 units wide. A platform bridges the widest one. I adjusted the layout once while reviewing, but I haven't confirmed in play that every jump is reachable. If the jumps feel too hard or too easy, adjust `JUMP_VEL`, `GRAVITY`, or the island positions in the level block.\n- Collision is a simple box-based system with no slopes, so it is not Sonic-accurate.\n\nIf you want, I can add a small test harness or tune the level layout after you've played it.",
 "ttft_ms": 24400,
 "type": "result",
 "duration_ms": 47039,
 "uuid": "[REDACTED]",
 "ttft_stream_ms": 1841,
 "time_to_request_ms": 253,
 "first_content_frame_ms": 1841,
 "queued_turn_count": 0,
 "result_index": 0
}

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