Not all creatures are available for purchase immediately. To unlock more creatures for purchase, you need to complete more sessions.
New creatures become available for purchase after a certain amount of sessions are completed:
0 Sessions – 6 Creatures
30 Sessions – 12 Creatures
60 Sessions – 18 Creatures
90 Sessions – 22 Creatures (All available)
Creatures that are available to buy is displayed with their relevant prices.
Creatures that are not available for purchase yet is displayed as a silhouette.
Creatures that are already owned are displayed as a washout.