Bonus 2 — The 15-Minutes-a-Day Play Calendar
Daily play isn't a luxury. It's part of the environmental enrichment in the main guide: it simulates the complete hunting sequence (stalk, chase, catch) that a cat needs to finish in order to feel satisfied, not just entertained.
Bonus 2 of the guide "30 Solutions to Cat Behavior Problems": 4 pages in PDF. You can buy it on its own, or get it included in the bundle with the guide and both bonuses.