P3 alpha: wolf moon every 7th night, the alpha breaks wooden doors, iron-banded door, broken-door repair, alpha pelt and cloak (protocol 7)

docs/PROGRESSION_DESIGN.md

@@ -1,6 +1,7 @@
 # Progression and challenges design
 
-Status: **P1 (iron) and P2 (stone) built**; P3-P5 are proposals.
+Status: **P1 (iron) and P2 (stone) built; P3 started (the alpha)**; the
+rest of P3, and P4-P5, are proposals.
 
 *As built in P1:*
 - Iron nuggets (70, in the scree under the rim), clay (60, on the lake
@@ -37,6 +38,19 @@ Status: **P1 (iron) and P2 (stone) built**; P3-P5 are proposals.
   windows still counts.
 - Palisade: 3 m tall, blocks like a wall online too. No fences.
 
+*As built in P3 so far (the alpha):*
+- Wolf moon: nights 7, 14, 21... (worked out from the day, so every game on
+  a server agrees). The moon turns red and a toast warns you.
+- The alpha (135 HP, bites for 16) comes out of the den with the pack and
+  leaves at dawn. It isn't afraid of fire and never runs. If it can't reach
+  you it batters the nearest shut door near you: a wooden door (or the
+  wooden leaf in a stone doorway or palisade gate) gives way after about
+  five blows and hangs broken until mended (E, 2 wood); then it comes in.
+- Iron-banded door (forge: 2 iron, 4 wood, 4 nails) can't be broken.
+- Drops: alpha pelt, 1-2 fangs, meat. Alpha cloak (+35 warmth) at the
+  workbench. Network protocol 7.
+- Not yet: the bear, crows and foxes, the barrow and its guards.
+
 Today the island runs out of goals after a few days: once you have stone
 tools, a hut, a bow and a fire, the only threats are wolves at night, the
 cold and your diet. This plan adds a **second tier of materials** (iron and