Objective. Have two rivers in the 21–26 range that strictly beat the opponent’s two highest in-range rivers. Busted or incomplete rivers do not count. Matching a value is not a win. When one player meets this condition, DEFCON begins: the opponent has one turn to match or beat the top two bids. If the lead survives, the challenger wins.

Opening. Draw eight cards. On each of your first three turns, place one Ace or number card onto a different, empty river. You cannot discard or disband until all three have started.

Later turns. Play one card and draw one, discard a card and draw one, or disband an entire one of your rivers (no draw). Players alternate turns.

Building. Only you can add numbered cards to your rivers. Your second number establishes ascending or descending direction. After that, each new number must continue that direction, or match the effective suit of the last number card. Consecutive equal ranks are always invalid. An attached Queen reverses direction and changes effective suit to the Queen's suit.

Jack (J). Attach to any number on either side; remove that number and its attached modifiers.

Queen (Q). Attach to any number on either side; reverse that river's direction and switch the effective suit. Queens can stack.

King (K). Attach to any number on either side; double that card's contribution. More Kings double again: 7 → 14 → 28.

Joker (★). Attach to an Ace to remove every other card of its printed suit from all rivers, or attach to a 2–10 to remove every other card of that rank. Target card stays.

Deck construction. Choose at least 30 cards from one standard 54-card set (including two Jokers). Different physical decks can contain duplicate suit/rank cards, but a single set cannot. This version includes one set, with a customizable 30–54 card deck.