Lesson 2 — The four safe first moves
Every Green Dot board admits four moves you can make in the first minute without any risk of a mistake. This lesson teaches them.
Move 1 — Rule out the second yellow
For every row that already contains a yellow dot, mark every remaining cell as "not yellow". Same for columns. This is safe: the constraint is absolute.
Move 2 — Rule out the third green
For every row that already contains two green dots, mark every remaining cell as "not green". Same for columns.
Move 3 — Fill forced greens
If a row needs one more green and only two of its cells are still candidates, one of those two is definitely green — but not yet known which. Note them as "one-of-two". Sometimes a column intersection resolves it immediately.
Move 4 — Fill forced yellows
If a row needs its yellow and only one cell is still a yellow candidate, that cell is yellow. Fill it. Same for columns. This is the highest-yield move — do it every time it applies.