Game 06 · Engine · measures: search
Connect Four, with the search exposed
The game is the excuse. The readout is the point: how many positions the engine visited, what it thinks each column is worth, and what alpha-beta pruning saves you.
You are brass — click any column to drop your disc.
brass = you · click any column to drop
Column evaluations
Play a move and the engine's per-column values appear here.
Turn pruning off at depth 6 and watch the node count climb by an order of magnitude for exactly the same move.
How it works
Negamax with alpha-beta over a 7×6 board, moves ordered centre-outward because centre columns participate in more winning lines and good ordering is most of what makes pruning work. The static evaluation scores every four-cell window: an open three is worth a lot, a blocked one nothing. Depth is plies, not moves — depth 6 means the engine sees three of your replies. The node counter is the honest measure of what the search cost, and the same position searched with pruning off gives you the ratio for free. Two-player mode skips the engine entirely — same board, no search.