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.
Sprite Fusion is a browser tilemap editor: you paint whole levels with regular and autotile layers and export the finished map to about ten engines; the web edition is free and its site listed the desktop edition at $14.99 (a limited-time price) on 2026-09-28. Nerulio Studio's Tile workspace is not a level editor — it turns a tileset into autotile rules the engine keeps using after export: a Godot 4 terrain set, a Tiled Wang set, Unity Rule Tiles or LDtk rules. Choose Sprite Fusion to finish a map in the browser; choose Nerulio when you will keep painting levels in the engine with its own autotiling.
- 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
Where the autotile rules live
In Sprite Fusion the rules live in the editor. An autotile layer holds rules, each a 3×3 pattern around the tile being resolved whose cells are Required, Empty or Ignored; the layer recalculates its tiles when you draw, fill or move content, falls back to Default tiles when no rule matches, and can pick among weighted variants. Rule sets can be saved and loaded as JSON presets. The export writes the map with the tiles already chosen.
Nerulio writes the rules into the tileset the engine loads. Each tile gets its terrain bits — recognised from the sheet's layout when it is a known one — and the export turns them into what the engine's own autotiling reads. Painting then happens in Godot, Tiled, Unity or LDtk, and the engine picks the tiles.
On the same 64 px cave blob-47 sheet (2026-09-23) that difference showed up concretely: Sprite Fusion's Godot 4 export loaded with 0 terrain sets and 58 cells baked into the map, and its TMX had no Wang set, while Nerulio's export was built by its importer into a terrain set of 47 tiles and 188 peering bits that Godot 4.7.2 painted exactly as predicted.
So the question is where the level gets finished. If the map is done in the editor and only needs to be loaded, baked tiles are fine. If designers keep editing levels in the engine, the rules must travel with the tileset.
- Autotile layer (Sprite Fusion)
- A layer whose tiles are recalculated from its 3×3 rules as you draw.
- Default tiles (Sprite Fusion)
- The fallback used when no rule matches a neighbourhood.
- Terrain set (Godot 4)
- The engine-side rules: tiles with peering bits that TileMapLayer painting and
set_cells_terrain_connectuse. - Baked tiles
- A map exported with each cell's tile fixed; the engine does no autotiling on it.
The same ideas in both tools
| In Sprite Fusion | In Nerulio Studio | In the engine after export |
|---|---|---|
| 3×3 rules per autotile layer (Required / Empty / Ignored) | Terrain bits per tile, from the recognised layout or the 3×3 bit editor | Godot peering bits, Tiled Wang IDs, Unity Rule Tile neighbours, LDtk 3×3 rules |
| Default tiles when no rule matches | No fallback: missing combinations are listed and outlined on the test map | Unity: Default Sprite; Godot: best-fitting tile or empty cell |
| Weighted variants in rules and defaults | A probability per tile | Godot: tile probability, set by the importer |
| Collision flag per layer | Collision polygons per tile, traced from alpha | Godot physics polygons (read back point for point in Godot 4.7.2) |
| Tileset width and height must be multiples of the tile size | Tile size, margin and spacing measured from the sheet | Margins and separation written into the Godot and Tiled tilesets |
| Export: the finished map with its tiles chosen | Export: the tileset with its rules, plus a sample map for Tiled and LDtk | Levels are painted in the engine with the same autotiling |
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 5 MB export cap; desktop edition $14.99 (limited-time price, 2026-09-28) |
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 that keeps a map GB Studio-compatible, with a 160 × 144 minimum-size overlay and a unique-tile counter.
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.
Other ways to do it
| Option | When it is the better choice |
|---|---|
| Sprite Fusion | You want to finish a level in the browser and ship it: regular and autotile layers, draw modes, tile attributes, a GB Studio mode, and map exports to Unity, Godot 3 and 4, Phaser, Defold, GDevelop, Bevy, Cocos, LÖVE and GB Studio, plus TMX, JSON, PNG and UVTT for virtual tabletops. |
| Nerulio Studio, then your engine | You keep painting levels in Godot, Tiled, Unity or LDtk and want the engine's autotiling to work there; your sheet has margins or 1 px spacing; you want to be told which combination is missing before it shows up as a hole. |
| Tiled or LDtk | You want a full desktop level editor whose own files keep the rules: objects, entities, worlds and automapping (choosing a tilemap editor). |
| Godot's own TileMapLayer editor | The game is in Godot and you are happy to set the terrain bits by hand in the TileSet editor (Godot 4 autotile). |
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
- Nerulio is not a level editor: no hand-placed tiles, objects, entities or tile attributes, and no level export beyond the sample map in the Tiled and LDtk bundles.
- Map targets are Godot 4, Tiled, Unity, LDtk and generic JSON only; no Phaser, Defold, GDevelop, Bevy, Cocos, LÖVE, GB Studio or UVTT exports.
- No default-tile fallback and no weighted variants inside a rule, only one probability per tile; no GB Studio mode.
- No desktop application; the Tile workspace was tested in Chromium only.
- 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.
Versions and sources
Nerulio side: docs/STUDIO-TILE.md, both tools driven in Chromium on 2026-09-23 with the same CC0 cave sheet; the 537-click figure is computed from the 47 rule masks, not timed. Sprite Fusion side: its own documentation and home page as read on 2026-09-28 (features, export targets, the 5 MB limit of the browser export, the tile-size rule for imports, prices). Features change; check its pages before deciding.
Official documentation used
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).