📜 Guide

Chain Reaction Game Rules Explained

The rules fit on an index card, but the second game always produces a question nobody can answer. This guide covers the card and the questions.

Setup

Two players, an empty rectangular grid (PlayCascade uses 6×6, 8×8 or 8×10 – see Board Sizes), each player with a colour. Players alternate turns; who starts can be set in the app.

Your turn

Add one marble to a cell that is either empty or already holds your colour. You may never place in an enemy cell. That is the whole move – the rest happens automatically.

Capacity

Every cell can hold one marble fewer than it has neighbours (orthogonal neighbours only, no diagonals):

Overflow

When the marble you add brings a cell up to its burst number, the cell overflows: it loses that many marbles and each neighbour gains one. Every neighbour that gains a marble becomes your colour, whatever colour it held before – and keeps the marbles that were already in it.

Cascade

If a neighbour reaches its own burst number as a result, it overflows too, and so on until every cell on the board is below its limit. Order does not change the end result in the two-player game; PlayCascade resolves cascades level by level and can show them step by step.

Winning

You win the moment your opponent has no marbles left on the board – with one exception: that check only applies once both players have made at least one move, so you cannot lose by being captured on turn one. There are no draws; a cascade that never settles is impossible on a finite board because each burst strictly reduces the number of marbles on the bursting cell.

Edge cases people ask about

• Can I place in a cell I just captured? Yes – it is your colour now.
• Can a cell hold more than its limit? Only for an instant during a cascade; it bursts before the turn ends.
• Does the overflowing cell become empty? In the two-player game it does, because it never holds more than its limit when it bursts.
• Can I pass? No. If you have any legal cell, you must place.

Once the rules are clear, the interesting question is where to put the first marble: Opening Moves.