In player order, players take turns choosing an obstacle and placing it into the play area until all obstacles have been placed.

• Asteroids must be placed beyond range 2 of each other asteroid and beyond range 2 of each edge of the play area.
• Gas clouds must placed touching (but not overlapping) an asteroid and beyond range 2 of each other gas cloud.

After a ship at range 0 of or obstructed by a gas cloud defends, if the defender suffered at least 1 c damage, each ship at range 0-1 of the gas cloud suffers 1 c damage. Then, remove the gas cloud.