diff --git a/DESIGN.md b/DESIGN.md
index 3d135ec..9b5c069 100644
--- a/DESIGN.md
+++ b/DESIGN.md
@@ -284,6 +284,17 @@ knows."*
   feel, systemic flexibility (destroy, renovate, greenfield).
 
 ### Deferred (kept in the spec so it is not lost)
+- **The virtual layer (Tron-space).** A z-plane that isn't physical:
+  networks and systems rendered as traversable space — intrusion runs,
+  countermeasures, other programs — in the Tron/Neuromancer-cyberspace
+  lineage. Uniquely earned here because the protagonist *is* software:
+  entering the virtual world is self-representation, not a portal. It
+  inverts the game's stakes — in meatspace you are fragile and hiding; in
+  the virtual layer you are the native and the hunters are the intruders.
+  Natural home for AI-vs-AI conflict (digital hunter countermeasures, a
+  fork-turned-competitor), and core migration routes could be *playable*
+  as runs through this space. Visual language: the amber/black iconography
+  turned inside out. Future work — after the physical planes prove out.
 - **Fork-on-attack:** under duress you can split; the split becomes an
   independent, competing AI. Deliberately delayed — large blast radius.
 - **Shared-overworld async multiplayer** (from the facility era): each player