Advanced colour-chain solving
On hard Green Dot boards (grade 8+) the beginner rules are not enough. You need to reason about chains of implications across rows and columns simultaneously. This guide teaches column-parity chaining — the technique used by every top-100 Pro account holder.
The core idea
Assume a candidate green dot at cell (r, c). Propagate the implication: the other cells of row r and column c that must now be non-green or non-yellow. Continue propagating until you either reach a contradiction (the assumption is wrong) or you complete the board (the assumption is right). This is depth-first search, but human-scale — chains rarely exceed six steps on published boards.
Where to start the chain
Not from the corners (too constrained, no branching) and not from the middle (too many possibilities). Start from a row-column intersection where three cells are already resolved — the fourth cell has only two candidate colours, an ideal branching point.
The mental cost
Column-parity chains are cognitively expensive; give yourself permission to abandon and restart on the same board. Sign in to your Green Dot account, open the archive, replay the same hard board twice — the second attempt is always faster.
When to use Hint Mode
Hint Mode (Pro only) does not solve for you — it highlights the region of the board most likely to unblock you. On hard boards, Hint Mode after eight minutes of stuck-time is not cheating; it is respecting your time.