Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/phuonghx/aim-cli/2d-gamesnpx skills add phuonghx/aim-cli --skill 2d-gamesgit clone --depth 1 https://github.com/phuonghx/aim-cliWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00096 | $0.01038 |
| Opus 5 | $0.00048 | $0.00519 |
| Sonnet 5 | $0.00019 | $0.00208 |
| Haiku 4.5 | $0.00010 | $0.00104 |
Grade A, and why
2d-games scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 113 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Building Games in 2D
A working reference for the systems that make a 2D game feel responsive and look coherent.
Sprites and Animation
Art that is loaded and drawn efficiently keeps frame times low and motion legible.
How to organize sprite data:
- Texture atlas — pack many images into one sheet so the GPU issues fewer draw calls. A character's idle, walk, and jump frames all live on a single sheet rather than as 30 separate files.
- Frame sequence — an ordered list of regions on the atlas, cycled to produce motion.
- Pivot point — the anchor used for rotation and scaling. Put a sword's pivot at the handle, not the center, so it swings correctly.
- Z-order — the integer that decides who draws on top. The player's z sits above the floor tiles but below the HUD.
Making motion feel alive:
- Animate somewhere between 8 and 24 frames per second depending on the style — chunky retro sprites read fine at the low end, fluid action wants the high end.
- Compress and elongate shapes (squash & stretch) on impacts and jumps to sell weight.
- Lead into a big action with a brief wind-up (anticipation) — a crouch before a leap.
- Let motion settle afterward (follow-through) instead of snapping to a stop.
Tilemaps
Grid-based levels are fast to author and cheap to render.
| Decision | Guidance |
|---|---|
| Tile dimension | Stick to a power of two — 16, 32, or 64 px — and stay consistent |
| Terrain edges | Lean on auto-tiling so corners and borders pick themselves |
| Collision data | Approximate with coarse shapes, not the exact painted pixels |
A typical layer stack, back to front:
- Backdrop — distant scenery you can never touch.
- Ground — the solid tiles the player stands on.
- Objects — chests, switches, pickups the player interacts with.
- Overlay — foreground elements that scroll at a different rate for parallax depth.
Collision and Physics
| Collider | Best for |
|---|---|
| Box | Crates, platforms, walls |
| Circle | Coins, bombs, anything round |
| Capsule | Player and enemy bodies |
| Polygon | Irregular hand-authored shapes |
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 113 lines · 96 tokens per session scan A 7b8291e2d359
2d-games is a skill published in the GitHub repository phuonghx/aim-cli (1 stars, last pushed 2mo ago), licensed MIT. It adds 96 tokens to every session and 1,038 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
Other skills, from other repositories
hs-release
Cut a core Hindsight release (vX.Y.Z) and open the changelog + blog PR. Use when asked to cut/start a release, bump the version, or publish a new Hindsight version.
research-repository
Build a repository that makes findings findable, reusable, and cumulative across teams. Use when the same research keeps getting redone. For synthesising one study, use affinity-diagram.
survey-design
Design unbiased survey instruments — question wording, scales, and sampling — to measure attitudes at scale. Use when you need quantitative breadth. For behavioural experiments, use a-b-test-design (prototyping-testing).
design-critique
Facilitate a structured team critique — framing, feedback rules, and actionable outcomes. Use when running a session with people in the room. For a solo expert review, use heuristic-evaluation (prototyping-testing).
handoff-spec
Write the implementation handoff — measurements, behaviours, assets, states, and edge cases. Use when engineering picks up the work. For verifying the result afterwards use design-qa-checklist; for reusable library components use component-spec (design-systems).
team-workflow
Design the team's operating rhythm — task management, collaboration rituals, and tooling. Use when the day-to-day cadence needs structure. For a time-boxed sprint, use design-sprint-plan.