* Random, variable rewards, with the possibility for really great rewards.
* In as many different ways as you can feasibly include.
* Optimise for 'near-misses', which have been shown to increase the addictive properties.
The more I've thought about it, the more I realize that variable reward is a key component of fun. All of the most fun and successful games have it built in, even if you don't realize it. Does it have ranked match making? That's variable reward. Why do you think online chess is so popular now? The ranked match making gives you just enough wins to keep you hooked.
Actually, Roger Caillois wrote a famous book on the different forms of play [1]. He uses four forms of play to classify games, and the one you are referring to is chance (Alea in his book). Another form of play that applies more accurately to chess is competition (Agon in his book). He also emphases two other key components of fun: playing a role (Mimicry) and physical sensations like in a roller coaster (Ilinx).
I certainly don't have any expertise or deep insight but I will say that one of the best videos I've seen on this is "The art of screenshake" by J. Nijman of Vlambeer [0]. There, he walks through what's a very basic 2d sidescroller shooter and adds in effects until it looks like an actual fun game. The idea being that layering feedback and effects so that every aspect of the game becomes more fun to play.
It sounds like this podcast was focusing more on Hearthstone and Marvel Snap, both games which I haven't played but are more strategy and luck oriented than the kind of games Vlambeer makes. I think one of the insights there is that there's a non-commutative aspect of the game that allows for different strategies based on context. For example, A > B, B > C but C > A, like in rock paper scissors, or some of its generalizations [1]. I think this is what Magic the Gathering did with each of the colors. Maybe the keyword here is "mixed strategies"?
Nijman's video highlights, to me, the importance of polish and how we basically understand that many core mechanics are fun and so don't need to be innovative if you add in enough polish or support around it.
One other thing I'll mention is that A. Bruce who developed Antichamber had a GDC talk about his process of development [2]. One of the interesting points he made was that he got it in front of players and watched how long they played. He tried to continually optimize for engagement, trying to get people to play a minute longer, etc. until he worked through to a fun game.
[0] https://www.youtube.com/watch?v=AJdEqssNZ-U
[1] https://en.wikipedia.org/wiki/File:Pierre_ciseaux_feuille_l%...
- Animal Crossing: your island may become overgrown with weeds, villagers want to move out, some furniture will rust, your home will have cockroaches
- Nintendogs: the puppies will get very hungry and thirsty, they'll lose weight and stop recognizing your voice.
Dopamine reward: Anticipation, something good happens, repeat
Addiction: Anticipation, something good happens sometimes, repeat
To answer the question from that standpoint, reward the player.. but not too much :)
Everything on top of that is there to get the person into the loop in the first place
This may have been good when games were pay once, but these days it's maybe something to stay away from.
So what is the tl;dr? What are we supposed to take away from this podcast episode?