Hubris is the axis around which a campaign of Age of Bronze revolves. The game is designed for you to reach a tragic end. This shouldn't be fought, but embraced. The number of Greek heroes who got home and lived happily ever after can be counted on one hand; even then, they usually weren't actually happy endings if you squint your eyes a bit (looking at you, Helen and Menelaus).
The tragic story arc is facilitated greatly by the Pendragon campaign structure, which we ported over wholesale. Just as with Pendragon, a campaign is one adventure per year, with a Winter Phase for you to take care of all that between session life stuff. All of that is mostly unaltered, though we have some rules about keeping up with appropriate sacrifices and such in order to keep the Olympians happy.
This pace helps. You can't tell that story inside a year or even two. For the most part, the Greek heroes took years to flame out. There are certainly the quick ends, like Icarus, but that wasn't the usual way it went and we have them covered, too.
So, what is hubris (as opposed to Hubris, which I'll get to at the end) as it's presented in Age of Bronze?
First of all, it's not simply pride, even larger than life, overweening pride. It certainly can be that, but that's a very small piece of the puzzle. Pride is certainly tied up in the whole thing, though. This might sound confusing, but there's a key to figuring out how telling a story about hubris and tragedy works.
Most importantly, we're working from the idea that religion is, at base, a way of communicating a society's values to its people. The stories, the deities, the heroes, the lessons... they're all there to let the listener understand what the rules are. The gods expect you not to kill, not to steal, etc. It's all fairly universal from culture to culture, with little tweaks here and there.
The interesting bit is when you take secularism out of the equation. There is no secular society offering "universal" values based on things like tolerance and human rights. Since laws govern mortal and immortal alike (and make no mistake, Zeus suffers for violating them as much as anyone else, when it's all said and done), all laws are deemed to have passed down from Olympus. The laws are the same whether you're in Athens or in Zeus' palace, right?
Here's where hubris comes in. Violating the laws of society is the same as violating the laws of Olympus, since they're one and the same. That is an extraordinarily prideful thing to do, just not in the way most modern people think of pride. In this sense, a minor crime like petty theft becomes hubristic; the thief has exalted himself above the laws of the cosmos. Not terrible, mind you; it's still a minor crime. It is still hubristic.
So as soon as the player hero steps off his farm into the wider world, he's set himself up for violating the rules. If society expects all men to be humble farmers or shepherds and all women to be mothers, doing anything else is preparing for a glorious, but guaranteed, fall. The hero leaves the farm, fights people, crosses the gods, disobeys the king, etc, etc. This is all hubris.
Of course, for every rule, there's a loophole. There's ample space to talk about the stuff which results in protagonist death which doesn't quite line up with these basic guidelines. That's okay! To quote the Age of Bronze rulebook:
Furthermore, the issue of hubris in the Greek world is one of incredible complexity and falls well outside of the scope of this game. There is a great deal of very interesting scholarship covering the ancient concept of hubris, and many readers would be surprised to find that some things they have always considered to be hubristic are not, while other things which never occurred to them are. Many of the great mistakes of the Greek heroes would probably not seem to be hubris at all to an ancient Greek (Orpheus looking back at Eurydice, which was mentioned in the opening of this chapter, is almost definitely not hubris in a traditional Greek sense, but it is equally definitely a very bad mistake which ruins his life and which causes the gods to make him suffer). These rules simply allow us to model the improper acts of Greek heroes and their consequences within the game world without devolving into an academic debate regarding semantics. Just remember that there is a difference between hubris, a complex word in Ancient Greek, and Hubris, a game mechanic in Age of Bronze and things should run smoothly.
Or, use the above about societal laws and divine laws being comparable as a jumping off point. Oedipus having relations with his mother isn't worse than Herakles braining people with his club, yet one is clearly deemed worse than the other in the context of their respective stories. It's okay to state that some things are of enough cosmic import to get several Hubris points.
Yes, Hubris points.
In Age of Bronze, the hubristic acts a hero commits nets Hubris points. Each character has a score from 1 to 20. 1 is a normal person, liable to do nothing much, while hitting 20 means it's time to have a tragic end for your hero and get the next one ready to play (probably one of your kids).
Theft is worth 1 point, while murder or trying to reach Olympus is worth 5 or more. The Gamemaster has room to play here, though we provide a pretty good list of different acts and their suggested penalties.
Getting from 1 to 20 without complications would be boring, so we prevent that by imposing penalties at 5, 10, and 15 points. At these break points, the hero encounters his Nemesis. Divine comeuppance is headed his way. The penalties are primarily there to make his life miserable, rather than kill him. The penalties are:
1) A +5 to all his Personality Trait rolls. He ends up being more extreme in his emotions, at the mercy of his feelings, which leads to more hubristic acts as he loses control.
2) A further -5 penalty for fumbling a Passion roll. The character ends up in longer and more severe depressions when they occur.
3) A directed trait related to the act which put the character over the top must be taken, at a score of 2d6. If Ariston drunkenly urinated in a stream sacred to Demeter, the Gamemaster might decide that he gets a Weakness for Mead directed trait of 2d6 attached to his Indulgent score. Again, this is about making the character more extreme in his behavior, which invariably leads to more and more Hubris.
4) An extra 1d6 is added to his city of residence's Weather rolls at the end of each year. Minor plagues, locusts, harsh winters, whatever. Things get tough for the city harboring a hero who has annoyed the gods.
These penalties are cumulative and Hubris cannot be decreased, ever. A hero going from 1 to 12 Hubris gets double the penalties (one set for 5 Hubris plus one set for 10).
While Hubris can never go down, a character can remove the penalties before they stack up. To do this, he must atone for his crimes. He visits an Oracle or a character (PC or NPC) who has the Divination skill. The Divination roll must be successful and only one roll is allowed per year.
If the roll is successful, the character is given a task to perform which, if successful, will remove the Nemesis penalties. The diviner or Oracle consults with the gods, finds out what's needed, and points the hero in the right direction.
In play, all of this adds up to a subtle but pronounced (especially when combined with Aristaea, which is another post) increase in the speed of Hubris accumulation. It's slow at first, but as heroes become more powerful and more unhinged, it comes more and more quickly.
In the end, Hubris never goes down. Every hero will hit 20, whether quickly or slowly. Once 20 Hubris is reached (and there's no Nemesis penalty for 20), the hero's player and Gamemaster sit down to chat about how to end things. However it shakes out, whatever's decided based on what's come before, the hero's career will end tragically. This is the chance for big, literary stuff. Shoot the moon. Make Orestes wish his tale was half as poignant and unsettling as yours.