Volfied (US) - MAME - Puzzle

You play the pilot of the spaceship Monotros, returning to his home planet, Volfied, to save it from an alien invasion. At the start of each level, the game board takes the form of a rectangle: your ship moves around the perimeter (the edge), while several aliens move around the inside. Any incursion by the ship into the rectangle allows it to cut through the board, leaving it vulnerable to enemy attack. Each closed zone you draw will then be validated. You will need to reclaim at least 80% of the game board to complete a level.