• ✓Number six on the brain-game shortlist (docs/brain-game-roadmap.md)
• ✓Asks WHICH SWITCHES MATTER, not what the rule is — because measurement showed one-at-a-time is not the fastest way to identify a rule
• ✓One-at-a-time is an attribution method, not a speed method
• ✓A claim is only accepted when the player's own runs contain a controlled pair: two settings differing in that switch alone, with different lamps
• ✓Eight of the ten rules have at least one switch that does nothing, so the question is real
• ✓Verified: all ten rules have distinct truth tables, and every level is winnable inside its budget
• ✓A fourth switch, and rules that depend on two at onceplanned

✓ = done · ☐ = planned. Every game is built one step at a time like this.