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 skills add vchelaru/FlatRedBall2 --skill top-down-movementgit clone --depth 1 https://github.com/vchelaru/FlatRedBall2Wrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/vchelaru/flatredball2/top-down-movement)<a href="https://agentmods.dev/skills/vchelaru/flatredball2/top-down-movement"><img src="https://agentmods.dev/badge/skills/vchelaru/flatredball2/top-down-movement/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/vchelaru/flatredball2/top-down-movement"><img src="https://agentmods.dev/badge/skills/vchelaru/flatredball2/top-down-movement.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
What 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 5.1 | $0.00057 | $0.01949 |
| Opus 5 | $0.00028 | $0.00975 |
| Sonnet 5 | $0.00011 | $0.00390 |
| Haiku 4.5 | $0.00006 | $0.00195 |
Grade A, and why
top-down-movement 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 5d 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 — 185 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Not for grid/tile-locked movement. If one key press should move the player exactly one tile (Pokémon, dungeon crawler, roguelike), use the
grid-movementskill instead.TopDownBehaviorproduces continuous analog movement — wrong for that use case.
Top-Down Movement
Overview
Top-down movement is provided by two classes in FlatRedBall2.Movement:
TopDownValues— a plain data class holding movement parametersTopDownBehavior— a component added to an entity that reads input and applies velocity/acceleration each frame
Minimal Setup
public class Player : Entity
{
private readonly TopDownBehavior _topDown = new();
public override void CustomInitialize()
{
var values = new TopDownValues
{
MaxSpeed = 200f,
};
_topDown.MovementValues = values;
var keyboard = Engine.Input.Keyboard;
_topDown.MovementInput = new KeyboardInput2D(keyboard, Keys.Left, Keys.Right, Keys.Up, Keys.Down);
}
public override void CustomActivity(FrameTime time)
{
_topDown.Update(this, time); // call from CustomActivity (after collisions)
}
}
TopDownValues Fields
| Field | Description |
|---|---|
MaxSpeed |
Maximum speed in world units/sec |
AccelerationTime |
TimeSpan to reach MaxSpeed from rest. TimeSpan.Zero = instant |
DecelerationTime |
TimeSpan to stop from MaxSpeed. TimeSpan.Zero = instant. Setting either accel or decel time to a non-zero value enables the ramp — no separate flag. |
UpdateDirectionFromInput |
If true (default), DirectionFacing follows input direction |
UpdateDirectionFromVelocity |
If true and UpdateDirectionFromInput is false, DirectionFacing follows actual velocity |
IsUsingCustomDeceleration |
If true, uses CustomDecelerationValue when entity exceeds MaxSpeed (e.g. after a knockback) |
CustomDecelerationValue |
Deceleration magnitude (units/s²) used when IsUsingCustomDeceleration is true |
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.
- 5d ago First seen · 185 lines · 57 tokens per session scan A 7683dc2dc64f
top-down-movement is a skill published in the GitHub repository vchelaru/FlatRedBall2 (14 stars, last pushed yesterday), licensed MIT. It adds 57 tokens to every session and 1,949 once invoked, about $0.0003 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 2026-09-04.
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