Strategically place your penguins to form groups and claim fish to score the most points! Turn order matters a lot; in Waddle, it's tracked by marbles on a two-column track! On your turn, you'll have two options:

"Place a Penguin" onto any unoccupied hex adjacent to the lowest numbered water hex. Then, pick up your marble and place it on the top of the same Turn Tracker column.
"Scout Ahead" by picking up and placing your marble on top of the inactive Turn Tracker column. 
How players "Scout Ahead" will be massively important! Going earlier in the future could allow you to grow or connect into a large waddle (group), claim a big fish, or block an opponent's important play.