▼March a column: every alien in it steps one row down.
✸Bomb: sacrifice a column's front alien. A bomb that lands on a gun damages and stuns it.
⌖After every move the guns answer: move, then fire up their column — but the beam only reaches the red kill zone. Point at a column to see their answer before you commit.
★Survivors carry over to the next siege. Each siege is harder than the last.