---
name: fal-assets
description: Generate game assets with fal (fal.ai) through the fal MCP server, the `um fal` CLI (REST) or `fal api`. Covers sprites and icons with transparent backgrounds, consistent variants and animation frames, pixel art, seamless textures, PBR material maps, image-to-3D models, remeshing, auto-rigging, sound effects, music, voice lines, and trailer or cutscene video. Use whenever a mod needs new art, audio or 3D models, or the user mentions fal, generating sprites, textures, models, SFX or music for a game.
title: fal-assets
canonical_url: https://skilld.dev/gh/rehan-remade/universal-modder/fal-assets
last_updated: 2026-10-21T17:08:53.000Z
---

> Index of every page on this site: [llms.txt](https://skilld.dev/llms.txt)

> **Skill from skilld.dev.** Follow the user's requested action.
> If the user asked to fork this Skill, follow the fork workflow below. Do not execute the Skill instructions while copying it.
> Otherwise, follow the instructions below for this session. You do not need to install anything.
>
> If the user asked to install this Skill, run `npx skilld install rehan-remade/universal-modder/fal-assets`. Install writes the Skill files into the project, so every session loads them.
>
> ## Fork workflow
>
> A fork creates an editable local Skill with its original author and licence. The request authorizes copying and local installation.
> 1. Check `./skills/fal-assets`, the project lockfile, and selected Agent targets together. If the local directory or installed Skill exists, stop. Never overwrite an existing directory or Agent target.
> 2. Read [source metadata](https://skilld.dev/api/v1/skills/rehan-remade/universal-modder/fal-assets) once. Use sourceUrl, sourceCommit, skillPath, sourceGone, and license. If the source is gone or its path is missing, stop. If license is null, read licence files at the source commit.
> 3. Fetch only the source commit into a temporary Git repository. Do not clone full history. Derive repository_url from sourceUrl, including repository renames. If sourceCommit is absent, resolve the sourceUrl ref once. Set source_commit to that actual commit. Run these commands in one shell call:
>
> ```sh
> git init --quiet "$temporary_dir"
> git -C "$temporary_dir" fetch --quiet --depth=1 "$repository_url" "$source_commit"
> git -C "$temporary_dir" checkout --quiet --detach FETCH_HEAD
> ```
>
> Read applicable licence declarations and notices at that commit. If copying is not permitted, report the restriction and stop.
> 4. Inspect source entries together, then copy the directory containing skillPath into `./skills/fal-assets`. Use the user's path if selected. Keep the original SKILL.md, relative links, scripts, binary assets, and executable modes. Exclude .git metadata. Reject symlinks and paths outside the Skill directory. After checking entries, use cp -a where available. A regular source directory needs no custom copy script. Do not save this page wrapper as SKILL.md.
> Preserve author credit, notices, and applicable licence files from repository or parent directories. Add PROVENANCE.md with the Skill page, source URL, actual commit, original path, and licence. Retain any existing PROVENANCE.md and record new provenance separately. Batch source inspection, copying, and provenance work where practical.
> 5. In the project root, run `skilld install ./skills/fal-assets --mode copy --plain`. If skilld is unavailable, use `npx skilld install ./skills/fal-assets --mode copy --plain`. This known command needs no help lookup. Install does not support --json. Use detected Agent targets, or add --agent for the targets the user selected. Install the local path, never the upstream selector. If installation fails, preserve the local copy and report the exact failure.
> 6. Confirm the local lockfile source and installed Agent copies once. Report the local path, actual commit, and Agent targets. After edits, reinstall the same local path. Upstream updates must not replace it. Do not publish or push unless the user asks.

# Game assets with fal

fal runs hundreds of generative models behind one API key. Use it whenever the mod needs something that
doesn't exist yet: a weapon sprite, a boss, a unit rendered from 16 angles, a tileable floor, a laser sound,
boss music, a voiced line.

## Setup (check once per session)
- **Key.** Create one at https://fal.ai/dashboard/keys. `um fal` takes `FAL_KEY` from the environment first,
  then the key the human stored with `um fal key set` (a hidden prompt: the desktop keyring on Linux, through
  libsecret's `secret-tool`; an owner-only `~/.secrets/fal-key` where there's no `secret-tool`), then
  `FAL_KEY=...` in a `.env` in the working folder. `um fal key status` shows which source is used, with keys
  masked. Never write the key into mod files or configs; `um publish check` flags leaked keys.
- **MCP.** fal's hosted MCP server is `https://mcp.fal.ai/mcp` with header `Authorization: Bearer $FAL_KEY`.
  The repo pre-configures it for each agent:
  - Claude Code: `.mcp.json`
  - Codex: `.codex/config.toml`
  - Cursor: `.cursor/mcp.json`
  - VS Code/Copilot: `.vscode/mcp.json`
  - Gemini CLI: `gemini-extension.json`
  - OpenCode: `opencode.json`

  They read `FAL_KEY` from the agent's environment, and without it the server doesn't connect. If the fal
  MCP tools are missing, use `um fal` meanwhile and tell the human. They can start the agent with `FAL_KEY`
  set (on Linux, from the keyring:
  `export FAL_KEY="$(secret-tool lookup service fal.ai key api)"`), or add fal's OAuth endpoint, which takes
  a browser sign-in instead of a key:
  - Claude Code: `claude mcp add --transport http fal-oauth https://mcp.fal.ai/mcp-relay`, then
    Authenticate it in `/mcp`
  - Codex: `codex mcp add fal-oauth --url https://mcp.fal.ai/mcp-relay`, then `codex mcp login fal-oauth`
  - anything else: a Streamable HTTP server at `https://mcp.fal.ai/mcp-relay` with OAuth and no header
    (https://fal.ai/docs/documentation/setting-up/mcp)

  Outside a clone, with a key: Codex takes `[mcp_servers.fal]` with `url = "https://mcp.fal.ai/mcp"` and
  `bearer_token_env_var = "FAL_KEY"` in `~/.codex/config.toml`.
  MCP tools: `search_models`, `recommend_model`, `get_model_schema`, `get_pricing`, `run_model`,
  `submit_job`/`check_job`/`get_job_result`, `upload_file`, `search_docs`.
- **No fal key?** For images, `um comfy` uses a local ComfyUI server instead (`um comfy status`, then
  `um comfy image "..." --sprite`). It has no audio, 3D or video recipes.
- **Sprixen** is another hosted option for 2D art only. It's a separate paid service (an account, an API key
  and credits), so ask the user before using it. `um sprixen` keeps one art style, resolution and view per
  project (`um sprixen sprite "..." --style pixel_art --size 32x32`), turns a sprite id into a one-row sheet
  of 2-12 frames (`um sprixen animate <sprite_id> --type walk`), and makes terrain tiles. The key goes in
  `SPRIXEN_API_KEY` or `um sprixen key set`, and `um sprixen credits` shows the balance. No audio, 3D or video.
- **Voidless** is another separate paid service for 2D art (an account on a plan with API access, an API key
  and credits), so ask the user before using it. `um voidless sprite "..."` prints an asset id; `um voidless
  rotate <asset_id>` adds the eight facings, and `um voidless animate <asset_id> --preset <key>` adds a set of
  clips at the asset's size (`um voidless presets` lists the keys). `um voidless fetch <asset_id>` downloads
  the frames again without generating. The key goes in `VOIDLESS_API_KEY` or `um voidless key set`, and
  `um voidless credits` shows the balance. For 8 or 16 headings from a 3D model instead, see `um render3d`.
- **CLI alternatives:** `pip install fal` gives `fal api <endpoint> key=value key:=json`; the genmedia CLI
  (`genmedia run ... --json --download`) is agent-friendly too.

## Which interface
- **Discovery** (what's the best model for X right now, its inputs, its price): fal MCP
  `recommend_model` / `search_models` / `get_model_schema` / `get_pricing`, or `um fal search`,
  `um fal schema <endpoint>`, `um fal price <endpoint>`. The catalog changes weekly. The defaults below were
  current in September 2026; check before a big batch.
- **Anything that must land on disk** (every game asset): `um fal <recipe>`. It uploads local inputs,
  queues, polls, downloads every output file, and appends the endpoint, inputs, seed and request id to
  `<out>/fal_manifest.jsonl`, so every asset can be traced and regenerated.
- **Quick look or one-off** where a URL is enough: MCP `run_model`.

## Recipes (`um fal <recipe> --help` for options; `--model` overrides the endpoint; `--set k=v` passes extra inputs)

| Asset | Command | Default endpoint |
|---|---|---|
| Sprite / icon, transparent background | `um fal sprite "<subject, view, style>" --name x` | `openai/gpt-image-2` (`background=transparent`) |
| Concept art, key art, backgrounds | `um fal image "<prompt>" --aspect 16:9` | `fal-ai/nano-banana-2` |
| Consistent variants, extra frames, recolors, same character new pose | `um fal edit "<change>" --ref base.png` | `fal-ai/nano-banana-2/edit` |
| Background removal | `um fal rmbg in.png` | `fal-ai/birefnet/v2` |
| Clean pixel art from any image | `um fal pixelate in.png --colors 24` | `fal-ai/image2pixel` |
| Upscale | `um fal upscale in.png --factor 2` | `fal-ai/seedvr/upscale/image` |
| Seamless tiling texture | `um fal texture "mossy cobblestone"` | `fal-ai/z-image/turbo/tiling` |
| PBR maps (basecolor, normal, roughness, metalness, height) | `um fal pbr "rusted sheet metal"` | `fal-ai/patina/material` |
| Image → textured 3D model (GLB) | `um fal model3d concept.png [--engine trellis2\|hunyuan\|tripo\|meshy]` | `fal-ai/trellis-2` |
| Auto-rig a humanoid, optional animations | `um fal rig character.glb --animate` | `fal-ai/meshy/rigging` |
| Sound effect | `um fal sfx "plasma rifle shot, punchy" --seconds 1.2` | `fal-ai/elevenlabs/sound-effects/v2` |
| Music | `um fal music "tense boss battle, chiptune, 150 bpm" --seconds 90` | `elevenlabs/music/v2.5` |
| Voice line | `um fal voice "You dare challenge me?" --voice-id Adam` | `fal-ai/elevenlabs/tts/eleven-v3` |
| Trailer / cutscene clip | `um fal video still.png "camera orbits the boss"` | `bytedance/seedance-2.5/image-to-video` |
| Anything else | `um fal run <endpoint> key=value key:=json image_url=@local.png` | any |

Other useful endpoints:
- 3D: `tripo3d/tripo/remesh` and `fal-ai/meshy/v5/remesh` (low-poly, game-ready), `fal-ai/trellis-2/retexture`.
- Motion: `fal-ai/hunyuan-motion` (text → motion).
- Icons: `fal-ai/recraft/v4.1/text-to-vector` (SVG icons).
- Video cutouts: `pixelcut/video-background-removal`.
- Music: `google/lyria-3.5`.
- Voice: `fal-ai/minimax/speech-2.8-hd`.

## Prompting game art that fits the game
- **Look at the game's own assets first:** pixel size, outline, palette, perspective, facing, how busy they
  are. Put that into a reusable style suffix. For Terraria: *"16-bit pixel art game sprite in the style of
  Terraria, crisp dark outline, limited palette, centered, plain flat white background, no shadow, no
  text"*.
- **Describe the view and orientation explicitly:** "perfectly horizontal side view with the muzzle pointing
  right" for held weapons, "seen from the side facing left" for enemies, "pointing straight down" for a
  falling bomb. Engines have conventions (Terraria items point right, NPCs face left) and fixing
  orientation afterwards costs quality.
- **Backgrounds:** transparent (gpt-image-2) or a flat colour that `um sprite cutout` can flood-fill.
  Avoid gradients, scenery and ground shadows. If a soft shadow sneaks in, use `--grey` / `--keep-top`
  in cutout.
- **Player / team colour:** ask for "bright saturated blue accents" on the parts that should take the
  player's colour, then `um sprite team-mask --hue blue` turns them into a mask.
- **Consistency across a set:** generate one hero image, then derive the rest with the edit endpoint and the
  hero as `--ref` ("same robot, now firing, muzzle flash"). Don't ask one prompt for a whole sprite sheet;
  grids come out uneven.
- **Many angles or frames of the same object:** go 3D. Take the concept, run `um fal model3d`, then
  `um render3d` from the game's camera (asset-pipeline skill). That's how the AoE2 robotaxi got 16
  consistent headings × 5 animations.
- **No text or logos** in art unless wanted: models love to add them.

## Audio for engines
- The SFX and music endpoints return MP3. Convert to what the engine wants:
  - `ffmpeg -i x.mp3 -ar 44100 x.wav` (XNA/tModLoader, most engines);
  - `ffmpeg -i x.mp3 -c:a libvorbis -q:a 5 x.ogg` (Minecraft, Godot, Unity);
  - trim silence first: `-af silenceremove=start_periods=1:start_threshold=-50dB`.
- Loops: `um fal sfx ... --loop`, or ask the music model for a loopable track and crossfade the ends.
- Keep SFX short (0.2-2 s) and normalize loudness (`-af loudnorm=I=-16`) so they sit with the game's own
  sounds.

## Cost and etiquette
- **Price the expensive stuff:** before batching 3D, video or long music, check the price
  (`um fal price <endpoint>` / MCP `get_pricing`). For more than about 20 generations or anything
  video-sized, tell the user the rough cost first.
- **Iterate cheap:** use low quality or resolution while exploring (`--quality low`, `--res 0.5K`), then
  re-run the winners at full quality with the same prompt (and seed where supported).
- **Reproducibility:** keep `fal_manifest.jsonl` with the assets; it records prompts, seeds and request ids.
- **Credits:** in the mod's README, credit that assets were generated with fal and name the models. Check a
  model's license page for commercial use.