Video by Kingston Kuan (@kstonekuan) · originally posted on XView original post on X
Claude Code (Claude Opus 4) vs Gemini CLI (Gemini 2.5 Pro)
Flappy Bird with two CLI agents
Kingston Kuan@kstonekuanHarness comparison7 likes2,726 views
Claude Code with Claude Opus 4 and Gemini CLI with Gemini 2.5 Pro each build Flappy Bird. Claude Code took one prompt at about $4; Gemini CLI was free but needed many fixes and switched models midway.
Each side pairs a coding harness with its own model, so harness and model differences are mixed. All harness comparisons.
Harnesses and models
| Harness | Model | Notes |
|---|---|---|
| Claude Code | Claude Opus 4Anthropic | One prompt; nice UI styling; about $4 (“~$4”).Written as “opus 4” |
| Gemini CLI | Gemini 2.5 Promedium confidenceGoogle | Free; lots of fixes after the first build.Written as “2.5 pro”Gemini CLI auto-switched from Gemini 2.5 Pro to Gemini 2.5 Flash midway (“slow response”). |
Details
| Kind | Side-by-side (same post, same prompt) |
|---|---|
| Task | Flappy Bird with two CLI agents |
| Topic | Flappy Bird (2D/3D) |
| Category | Games |
| Mode | Not stated |
| Posted | |
| Video length | 12.1 s (+1 more clips) |
| Likes / views | 7 / 2,726 · as of Oct 18, 2026 |
| Bookmarks | 1 |
| Sponsored | No |
| Original post | x.com/kstonekuan/status/1938256653088133518 |
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