Trains: Irreversibility — the felt experience of path dependence. Borrows from Johnstone's New Choice mechanic but enforces forward rather than replacing.
Setup: Two players do a scene, 3-5 minutes. A coach watches for any attempt to retcon, undo, or contradict previously established facts. When a retcon happens — "Actually, I meant..." or "Wait, no, we're not in a hospital" or even subtly ignoring an established detail — the coach calls "Keep it!" The scene does NOT rewind. The player must justify and continue from the unwanted thing, making it true. This teaches irreversibility by enforcing it: the retcon attempt itself becomes an established fact that must be honored.
Side-coaching: "Keep it — that's real now." "Don't drop that." "Where did the hospital go? It's still here." When players freeze after being called: "You don't have to fix it. Just build forward from where you are."
What to notice: How often you instinctively try to edit history. How the impulse to retcon is almost always driven by fear — fear that the last offer was "wrong," fear that the scene is going in a direction you didn't want. Notice that every time the coach forces you forward, the scene finds territory more interesting than what you were trying to get back to.
Common failures:
- Freeze after being called — players stop dead, afraid to move. Coach: "The scene didn't stop. Keep going."
- Subtle retcons — not saying "no" but simply ignoring a detail until it decays. Harder to catch, more damaging.
- Over-monitoring — players become so afraid of retconning that they stop making offers. Coach: "Being bold is more important than being careful."
The deeper lesson: Irreversibility is not a punishment — it's the source of all dramatic stakes. If you could undo anything, nothing would matter. The permanence of your choices is what gives them weight. The skill being trained is not memory but justification — the ability to build forward from any point, including the point you didn't want to be at.
Variation — Fact-Check Scene (separate exercise, different muscle): A third player sits to the side and tracks every established fact. At any point they call out "Where's the gun?" or "What happened to Bob?" forcing the scene to account for dropped details. This trains active listening and coherence more than irreversibility — it's a continuity drill, not a commitment drill.