Uniform layouts and diagonal quota
Choose 3, 4 or 5 hazards on a 4×4 grid. Exactly one hazard lies on the main diagonal A1–B2–C3–D4. The other hazards occupy off-diagonal cells. All 264/880/1980 legal layouts respectively have equal probability. One random layout stays fixed throughout the round.
Counting compatible layouts
Initially each main-diagonal cell is safe with probability 3/4. With 3 hazards, each off-diagonal cell is safe with probability 10/12. A safe first diagonal cell from a 20-coin stake gives 20×0.97/(3/4), about 25.867 coins; an off-diagonal safe cell gives 23.28. Later safe probabilities use only compatible layouts, and can increase or decrease.
Expected return and variance
Exact expected return is97% for permitted stopping policies. The initial3% reduction is applied once; conditional safe-branch compensation preserves expectation. Choosing coordinates or stopping changes risk and variance, not this expectation. A short session is not guaranteed to match it.
Collecting and eligibility limits
Collect is available after a safe reveal. Proven hazards are unavailable; proven-safe cells have probability1 and add no value. A choice with next value above1000 times stake is unavailable. When no eligible uncertain choice remains, the current value is banked automatically. The guard is not a promise that1000×stake can be reached.
Wallet persistence and refill
Settled balance and fractional payout carry persist in localStorage. Reloading during a round ends it without refunding its already deducted stake. Outside a round, refill restores1000 coins when balance is below the smallest stake; it does not add1000 or reset fractional carry. Hazard count, stake and refill are locked during play.
Frequently asked questions
Is this an operator website?
This independent 1930 Cup guide supplies its own free Diagonal Quota Mines demo. Operator identity, domains, licence, apps, payments, support and commercial game equivalence have not been independently verified. No operator account or commercial link is supplied here.
What is the main-diagonal rule?
Choose 3, 4 or 5 hazards on a 4×4 grid. Exactly one hazard lies on the main diagonal A1–B2–C3–D4. The other hazards occupy off-diagonal cells. All 264/880/1980 legal layouts respectively have equal probability. One random layout stays fixed throughout the round.
How is the live value calculated?
Live value starts at0.97 times the virtual stake. A safe reveal divides it by that cell’s exact conditional safe probability among the remaining compatible legal layouts. A hazard ends the round with zero return. Reveals change knowledge, not the hidden layout.
How are safe probabilities counted?
Initially each main-diagonal cell is safe with probability 3/4. With 3 hazards, each off-diagonal cell is safe with probability 10/12. A safe first diagonal cell from a 20-coin stake gives 20×0.97/(3/4), about 25.867 coins; an off-diagonal safe cell gives 23.28. Later safe probabilities use only compatible layouts, and can increase or decrease.
Explore the free Diagonal Quota game and its exact conditional cell odds.
