Scythe uses an ongoing action-selection mechanism (no rounds or phases). Players take turns one after another until a player places their 6th star on the board, immediately ending the game.
On your turn, do the following in sequential order:
1. Place your action token on a different section of your Player Mat than where it was on your previous turn.
2. Take the top-row action on that section once (optional).
3. Take the bottom-row action on that section once (optional).
Thus, you may take a single action, both actions (from top to bottom), or neither action (but you must still move your action token). You may use resources gained from the top-row action to pay for the bottom-row action. Also, you may complete an objective card during your turn.
The costs (red boxes) and benefits (green boxes) on your Player Mat are shown by the number of empty spaces before the action is taken. When taking an action, first pay the cost, then gain as much or as little of the benefit as you wish. You may only take an action once on your turn, not multiple times.
After you’ve completed your turn (or as you’re finalizing your decision on a bottom-row action—it is crucial for turns to overlap in this manner to keep the game moving at a steady pace), the next person in clockwise order takes their turn.