First it's a great book, and give some great suggetions and a great tool: machinations. The book covers a lot of topics. I want to share some ideas I got. The ideas are about emergence game design, not progression game design. 1. Design simple mechanic, not complex mechanic. Then combine several simple mechanics into one game. 2. The game complexity is increasing very fast after combining several mechanics. You can't balance the game before you combining the mechanics. In short, you have no way to balance the game when you design it. 3. The attached tool machinations is a good tool for game balancing by monte calo simulation. 4. Add negative feedback is a way to balance the game. 5. If you want to make the gaming progress fluctuate largely, frequently use bigger delay time for each action. For instance, the health postion restore 5HP not instantly, but after one turn or two turns. 6. Frequent probability with small effects won't let down the player. There is one game. "slay the spire" is a good example. Now I want to add cards mechanic into no matter what games.