How do you create a system of game mechanics that best creates the opportunity for interesting, emergent behavior in combination with each other?
Many games have interesting combo systems, and some are better than others. Magic: The Gathering and Terraforming Mars. Skill trees in Diablo III or World of Warcraft.
What are techniques for designing a set of mechanics that have interesting combos? What types of combos are there? How can a set of mechanics be evaluated for how interesting their ‘combo’s are? Is it a systemizable problem? How can it be made fun and comprehensible? What is the best I could do procedurally?