diff --git a/CHANGELOG.md b/CHANGELOG.md
index d948862..d1779c9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -40,6 +40,10 @@ There are two downloads: **full** (launcher + level editor) and **launcher** (mo
     Boot to level) no longer damages your progress.
   - The level tally shows the real coin and secret totals of new levels, the Test World and the
     arena instead of the Village's "55".
+  - **New: Alligator Arena** – a minigame on a TestLevel chapter (default 49): alligators come in
+    waves into a walled pit; every hit costs one of their lives and coins pop out, their bite
+    costs your energy; beat every wave and the exit opens. Lives, waves, energy and coins per hit
+    can be set.
   - **New: Llama Coaster** – a roller-coaster ride on a TestLevel chapter (default 48), with the
     cart from the Catacombs: drops, climbs, boost arrows, a jump and a spin pad. Two tracks, 1–3
     laps, three speeds.
@@ -81,7 +85,15 @@ There are two downloads: **full** (launcher + level editor) and **launcher** (mo
   - Opcodes have checked descriptions.
 - Narrow docks, small windows and long labels wrap instead of being cut off.
 
+### Documentation
+
+- New guide for building your own levels, a reference of the game's file formats and engine
+  limits, and a chapter on object scripts (strats) with the arena and the coaster as worked
+  examples: start at [docs/README.md](docs/README.md).
+
 ### Known limits
 
 - Tested on Linux (Wine) and in a Windows VM. Real Windows hardware is not tested yet.
 - The game draws objects only within about 12 units of the llama.
+- Four music tracks of the game have no file on the CD (GAMEOVER, TALLY, PUZZLE2, PLATFORM); the
+  editor marks them.
diff --git a/README.md b/README.md
index 9def158..73c107d 100644
--- a/README.md
+++ b/README.md
@@ -20,16 +20,16 @@ More pictures:
 
 | | |
 |---|---|
-| ![LlamaMod launcher](docs/img/launcher.jpg) | ![Level editor](docs/img/editor.jpg) |
-| **Launcher**: mods with options, save-game editor, one-click play | **Level editor**: brushes, tiles, meshes, objects, textures, play-test with F5 |
 | ![Test World gallery](docs/img/testworld-gallery.jpg) | ![Alligator Arena](docs/manual/img/mod_arena.jpg) |
 | **Test World**: all 253 figures and objects of the game in one level | **Alligator Arena**: a minigame with new, scripted enemies |
-| ![Debug view](docs/img/debug-view.jpg) | ![glTF in Blender](docs/img/gltf-blender.jpg) |
-| **Debug view**: collision and invisible objects in the running game | **glTF/OBJ** export and import for Blender |
+| ![Llama Coaster](docs/manual/img/mod_coaster.jpg) | ![Debug view](docs/img/debug-view.jpg) |
+| **Llama Coaster**: a new roller coaster track for the catacombs cart | **Debug view**: collision and invisible objects in the running game |
+| ![glTF in Blender](docs/img/gltf-blender.jpg) | |
+| **glTF/OBJ** export and import for Blender | |
 
 ## Features
 
-* **Mods** – tick, *Apply*, *Play*: Test World, Alligator Arena, your own levels, Boot to level,
+* **Mods** – tick, *Apply*, *Play*: Test World, Alligator Arena, Llama Coaster, your own levels, Boot to level,
   Intro skip, Mirror mode, Practice tools (save/restore position, extra checkpoints), Randomizer,
   Draw distance, Built-in cheats, Debug wireframe, Free camera & noclip.
 * **Level editor** – new levels from templates or editing the original levels; brushes, the base
diff --git a/docs/img/editor.jpg b/docs/img/editor.jpg
index 65842ff..f163feb 100644
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diff --git a/docs/img/launcher.jpg b/docs/img/launcher.jpg
index 17f17ae..d2db3cf 100644
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