The cost for the player Actions is measured in Resource Blocks of a given colour that the active player must pull from the HQ Tower, which are then replaced on top of the Tower. Blocks may not be pulled from the top 3 rows of the Tower.
When removing Resource Blocks from the HQ Tower, the active player may only use one hand and may only touch one Block at a time. They may check to see which Blocks are loose before attempting to pull one.
The active player is the person currently taking their turn, except when paying the cost of and resolving Directive Cards (see 'Play Directive Cards'), when the active player is the person who played the Directive Card.
When pulling Resource Blocks from the HQ Tower, the player clockwise of the active player may use one finger to steady the HQ Tower.
If the HQ Tower collapses, immediately rebuild the Tower in a random configuration and resolve the next 5 Events. Players cannot play Directive Cards or take Actions while these 5 Events are resolved. Then, if the lose condition has not been met, draw and place 5 Event cards face down, replacing the resolved Events.
It is also possible to pay for Actions with gathered Inspiration Cubes and/or Unlocked Blocks. See also 'Inspiration and Unlocked Blocks' for more details.