Time is the currency of opportunity. This is true in life and in games, and lately I’ve had some small thoughts regarding this.
In life, the act of saying yes to something that takes your time is also the act of saying no to other opportunities. Of course, new freelancers will trip on this and say yes to things they can’t truly commit to, but overall time is your currency for opportunity. We see this in small-scale ways (choosing between dinner with friends in town or going to your regular game night), in medium-scale ways (picking between two job offers or two major contracts when you only have one), and in large-scale ways (deciding whether or not to be a parent).
In games and stories, this philosophy is useful for creating drama and consequence. The classic is the superhero “save the person you care about or that busload of orphan nuns.” In games, we highlight this tension by creating mechanics that promise the chance of getting both results, though the likelihood that you’ll get only one (and the risk of getting neither.) Great mechanics for this can be found in the various *World games (like Dungeon World, Apocalypse World, etc.) and its predecessor Otherkind Dice.
Fundamentally, this is where skill rolls for observational/informational tasks can become interesting: does this task cost you an opportunity? And that is where tension lies. If there is no cost, then such things are free. And basic human psychology tells us something key: we don’t really value things that are free. So let’s make such things cost.
But this isn’t just an “indie” thing. Most games have this built it as a function of, well, linear time and turn-taking. When you do an action of some sort of Pathfinder, you’re doing that action to the exclusion of similar actions. Which spell are you going to cast right now: the one that buffs your friends or whacks a foe? Do you do the attack that is riskier but with a better payoff, or the attack more likely to hit but not as strong an effect?
So, when we’re designing systems, let’s not just look at binary success/failure, but at relative cost. Let us engage emotionally with the moment because we’re risking the most basic currency we all have: time.
 I think at this point, Dungeon World has more mindshare than Apocalypse World does, at least outside of indieland. Which is, at least to me, an interesting and important observation about our communities.