Sprite Fusion Alternative — Autotile Rules Kept in the Engine
Sprite Fusion is a free web tilemap editor: you paint whole levels with layers and hand-made 3×3 rules, then export the finished map to about ten engines. Nerulio Studio's Tile workspace has a narrower job — turning a tileset into autotile rules the engine itself keeps using. Both were given the same 64 px cave blob-47 sheet; the difference is how the rules are made and whether they are still there after export.
- Godot 4 TileSetVerified· Godot 4.7.2
- TiledVerified· Tiled 1.12.2
- Unity 6 Rule TileVerified· Unity 6000.5.3f1 + 2D Tilemap Extras 8.0.3
- LDtkPartly verified· LDtk 1.5.3 schema + loader
What it does
- The layout is recognised from the pixels instead of drawn rule by rule: 7 actions and 4.5 s from the sheet to a Godot terrain set of 47 tiles with 188 peering bits.
- The rules leave with the tileset: a Godot 4 terrain set built by an import script, a Tiled Wang set, one Unity Rule Tile per terrain, and LDtk rules (partly verified).
- The test map (M) paints with Godot's rule or Tiled's rule, so you see what the engine will draw — including where it leaves a hole or substitutes a tile — before you export.
- Tile size, margin and spacing are measured from the sheet and shown as a dashed preview until you press Use this grid.
Nerulio Studio and Sprite Fusion on the same tileset
The same 64 px cave blob-47 sheet, both tools driven in Chromium on 2026-09-23.
| Nerulio Studio | Sprite Fusion | |
|---|---|---|
| From the sheet to working rules | 7 actions, 4.5 s; layout recognised from the pixels | 12 setup actions, then 537 clicks to set the 47 rules by hand (counted from the masks) |
| Rules in the Godot 4 export | Terrain set with 47 tiles and 188 peering bits, built by the import script | 0 terrain sets; 58 cells baked into the map |
| Tiled export | .tsx Wang set + sample.tmx (verified in Tiled 1.12.2) | TMX without a Wang set; tileset repacked to the 24 tiles used |
| Map drawn correctly | Godot 4.7.2 painted 485/485 test cells as predicted | 58/58 inside its own editor once the rules are complete |
| Unity and LDtk | One Rule Tile per terrain (verified); LDtk rules (partly verified) | Map exports with tiles baked, no rules |
| Level editing | Test map only: no objects, entities or level export | A full map editor: layers, pencil, fill, selection, attributes |
| Tile size, margin, spacing | Measured from the sheet | One tile size per project; import does not ask for margin or spacing |
| Price | Free, runs locally | Free on the web with a 4.5 MB export cap; $14.99 desktop edition |
Source of these numbers: docs/STUDIO-TILE.md (Competitors, 2026-09-23), research/competitors/TILE-TEXTURE-UI.md
Where Sprite Fusion is the better choice
- It is a real tilemap editor: layers, pencil, fill, selection and per-tile attributes. You can build the whole level there; the Studio's map is only for testing rules.
- It exports finished maps to about ten engines — Unity, Godot 3 and 4, Cocos, Phaser, GDevelop, Bevy, LÖVE, Defold, GB Studio — plus TMX, JSON, PNG and UVTT for virtual tabletops.
- Rule outputs can carry % weights for random variation, and rule lists can be saved and loaded.
- A GB Studio mode and a CRT view for retro-styled projects.
How to do it
- Drop the tileset on this page; it opens in the Tile workspace with grid candidates.
- Press Use this grid, then Apply the first layout candidate.
- Read the Check panel and paint on the test map (M) with the Godot rule or the Tiled rule.
- Export for Godot 4, Tiled, Unity or LDtk, and keep painting the real level in that editor with the same rules.
Engine exports and how each was checked
"Verified" means the exported files were loaded by the real engine or tool on real CC0 assets and the result was compared with the source. Anything that was not loaded is labelled as such.
| Target | Files | Check |
|---|---|---|
| Godot 4 TileSet | PNG · nerulio-tileset.json · nerulio_tileset_import.gd | Verified Godot 4.7.2The included import script builds the TileSet with terrain peering bits; a map painted with set_cells_terrain_connect equals the Studio preview in every cell on 9 corpus sheets. |
| Tiled | .tsx Wang set · sample.tmx | Verified Tiled 1.12.2Tiled's own readers load every Wang ID as written and the sample map renders pixel-exact. The terrain brush itself was not driven. |
| Unity 6 Rule Tile | nerulio-ruletile.json · Editor/NerulioRuleTileImporter.cs | Verified Unity 6000.5.3f1 + 2D Tilemap Extras 8.0.3Blob and side sets: a painted Tilemap shows the predicted sprite in every cell. Corner / dual-grid sets are not exported to Unity. |
| LDtk | .ldtk (1.5.3) · rules · sample level | Partly verified LDtk 1.5.3 schema + loaderAccepted by the LDtk JSON schema and its official loader, and the rules re-run to the exported tiles; not opened in the LDtk app. |
Evidence
Layouts identified from the pixels alone on the tile corpus: 4 blob-47 templates and 2 Wang templates with high confidence, a real 64 px cave tileset with medium confidence — every tile's bits right. Godot 4.7.2 painted every test cell exactly as the Studio predicted (485/485 per blob set, 251/251 on a 4-terrain dual-grid pack); Tiled 1.12.2 read every Wang ID back; Unity 6000.5 matched on every painted cell of the blob and side sets.
Limits
- Tiled's terrain brush, the LDtk app and Godot's editor painter were not driven; the checks use the engines' readers and set_cells_terrain_connect.
- Unity gets blob and side sets only; several terrains become several Rule Tiles with no transitions between them.
- Isometric and hex tiles, animated tiles, occlusion and navigation layers are out of scope.
- Suggesting bits without a known layout needs a reference "full" tile; on side-only path templates the guess can fail until you select it.
Questions
Can I keep painting with my autotile rules in Godot after I export?
From the Studio, yes: the import script builds a TileSet with terrain peering bits, and Godot 4.7.2 painted all 485 test cells as predicted. Sprite Fusion's Godot 4 export loaded with 0 terrain sets in our test — its tiles arrive baked into the map.
Where does the 537 clicks figure come from?
It is counted from the 47 rule masks the sheet needs, set one cell at a time in Sprite Fusion's rule list — not timed by hand. When tiles were assigned through its interface in the test, 3 of 47 landed in the wrong rule.
Is the Studio a level editor like Sprite Fusion?
No. The test map exists to check rules; it has no objects or entities and exports no level beyond the sample map written with the Tiled and LDtk tilesets. Build the level in Godot, Tiled, Unity or LDtk.
Is it free, and do I need an account?
Everything on these pages is free and works without an account. There is no watermark and no export that is held back.
Are my sprites uploaded?
No. The Studio decodes, packs and exports in this browser tab. Projects are autosaved in the browser (IndexedDB) and can be saved as a .nerulio file.
Does it need Aseprite or an engine plugin installed?
No. .aseprite files are read and written in the browser, and each engine bundle carries what that engine needs (for Godot, the import settings and scene; for Unity and the Godot TileSet, a small editor script).