Handling Disadvantages

Disadvantages with self-control rolls can derail a session, but that is not a bug; it is a feature. You got the character points, so you paid the price. A good yardstick is one to three rolls per session, but only when the disadvantage is relevant. If a disadvantage is not relevant, it is not a disadvantage, such as a "fear of deserts" in a game that happens on an ice world, or "angry with orcs" on a fantasy world with no orcs. It is also easy to go overboard in calling for rolling in mildly relevant situations.

This is sort of how we always handled disadvantages, being fair while keeping them meaningful. You got the points; it has to mean something, but a disadvantage shouldn't be used punitively against a player or their character.

But one to three rolls (per session) seems fair; this is how we handled them, and you don't always have to trigger the disadvantage during a session or adventure. My rule is that the disadvantage must be meaningful in the story. If a disadvantage would cause a delay, change plans, derail the story, or result in some other serious consequence, it is worth considering. Situations that matter need dice rolls.

If it is minor and does not matter in the context of the current story, like "likes to live the high life" and the character is on vacation, fine, don't roll, just spend a little more money to cover it.

And players can elect not to roll and just indulge or succumb to the motivation! This is good roleplaying, and it saves the game from being subservient to the dice. Give the player a CP award for good roleplaying at the end of the adventure, especially if it made the entire situation more difficult, memorable, or more fun.

Roleplay over rolls!

Some self-control rolls have durations, such as once every 10 minutes. A "party animal" at a party will need to keep making rolls, or they will join in. If they are trying to get something important done, like sneak into an office and sort through a file cabinet, they will need to keep making rolls every so often as long as they are there.

When you can use a self-control roll to increase tension, forcing periodic checks, use it if it makes sense.

Do not use self-control rolls or disadvantages to make a character unplayable. There is such a thing as a horrible design in GURPS, with a character taking 10 different disadvantages with self-control rolls, and them becoming unplayable due to the amount of distractions they need to roll for; moderation is key. But a character should not be punished for taking one and then "having it constantly used against them." This requires a good handle on refereeing and fairness, and not overusing a disadvantage by forcing the player to roll for things that aren't important or by constantly forcing checks.

Also, be fair and apply disadvantages equally. It is easy to fall into a habit of "picking on the most fun character" with the iconic disadvantage, but other players made these picks too, and you should not favor one over the other. You get characters that will stand out and "be the most fun," but resist the urge and give everyone's disadvantages time to impact the game.

Also, I always throw a secret "reaction roll" in any failed self-control roll. How bad is it? In a critical failure, things could go completely sideways, but there is a chance something good could come of it. A critical success may mean our gambler, who gave in to an urge, gets invited to the "high stakes room" where a contact is made, or they meet a fellow gambler who turns out to be a valuable NPC to know.

The advantage-and-disadvantage system is one of the best parts of GURPS, which makes it so different and more fun than 5E, and we loved it because it gave our characters realistic mental and physical traits that impacted the story. Today's games are more concerned with "power builds" and what a level system can give a character at every level.

GURPS cuts differently, and we loved this system. It always made our games more than "just playing through an adventure," and the characters' reactions changed depending on who they were. That room with the gold goblet? A greedy character would take it for themselves, while a pious one would donate it to a church. A normal character may take it for gear and supplies. A character uninterested in wealth would ignore it. The pious and greedy make a grab for the goblet first, and the shiny treasure may make them forget to check for the trap that will trigger when it is taken, or it may incur a penalty since the gleam of gold is so distracting.

This stuff matters.

In a d20 game? That goblet and trap are there, and a part of the room description. The characters, be they paladins or thieves, really don't matter since they are all the same inside their heads. The "best player syndrome" makes my thief extra careful and incurs no penalty for my paladin, considering the danger it may cause. My paladin can't even "search for traps" in a modern game, as it isn't a skill the designers typically give them.

GURPS makes it all matter.