Filler — Strategy

Denying a colour

The opponent may not take your current colour. So each move not only takes cells but also forbids the opponent one colour on their next move.

When denying a colour beats taking cells

Look at the opponent's border. If they have a big patch of one colour next to them, take that colour yourself — even if it gives you little or nothing. The opponent cannot take the patch right away, and you gain a move to get closer to the patch or to cut it off.

A move that captures nothing is allowed by the rules. It is justified when the opponent's patch is bigger than what another colour would give you.

A ban lasts one move

With two players you must change colour, so on your next move you lose the ban yourself. The denied patch does not disappear: a move later it is available again. So a ban is good when in that move you can either take the patch yourself or cut it off, or when the opponent has two such patches and cannot close both at once.

When both need the colour

If a big patch borders both you and the opponent, whoever takes its colour first takes the whole patch. Such a colour is almost always worth taking at once.