Update ROADMAP.md

ROADMAP.md

@@ -8,6 +8,56 @@ The roadmap now tracks playable vertical slices rather than early technical boot
 
 ---
 
+## Slice 0: Vault 109 Onboarding
+
+### Goal
+
+A first-time player joining a Commonwealth Online server is placed into Vault 109, creates their character, sets SPECIAL stats, receives basic server context, and exits into the Commonwealth as a valid multiplayer character.
+
+### Player Experience
+
+1. Player opens Multiplayer from the main menu.
+2. Player joins a server.
+3. If the player has no character/save for that server, a new character is created.
+4. Player spawns in Vault 109.
+5. Player customizes appearance.
+6. Player completes the Vault 109 SPECIAL setup process.
+7. Player receives basic lore/context for the server.
+8. Player exits the vault.
+9. The server/client marks onboarding as complete.
+10. Future joins spawn the player from their saved multiplayer state instead of restarting Vault 109.
+
+### Includes
+
+- Vault 109 interior
+- First-join detection
+- New multiplayer character creation flow
+- Appearance setup
+- SPECIAL setup
+- Intro quest or onboarding state
+- Vault exit sequence
+- Save/profile persistence
+- “Cannot return after leaving” rule if desired
+
+### Internal Milestones
+
+- [ ] Create Vault 109 start cell
+- [ ] Add first-spawn marker
+- [ ] Route first-time server players to Vault 109
+- [ ] Open appearance customization
+- [ ] Build SPECIAL allocation flow
+- [ ] Save onboarding completion state
+- [ ] Move player to Commonwealth exit point
+- [ ] Prevent repeat onboarding for existing server characters
+- [ ] Test joining same server again
+- [ ] Test joining a different server for the first time
+
+### Done When
+
+A player can join a server with no existing multiplayer save, create a character in Vault 109, assign SPECIAL stats, leave the vault, reconnect later, and continue as the same character.
+
+---
+
 ## Slice 1: Same-Cell Multiplayer Foundation
 
 ### Goal