For our GURPS campaigns, these are things you can get by spending points in play. While it's possible to actually spend character points on these things, you should spend karma points instead.
It costs 2pt to go between crit and regular, and 1pt to go between regular failure and regular success. You can also increase the margin of a regular roll for 1pt. Note that this is a metagame action, so you can use it to buy failure in case your character is mind-controlled into attacking your teammates or the like.
This makes a permanent change to the situation or setting, adding/moving/etc. an NPC or object. Negotiation between the player and GM is recommended, and can often tweak a change so it fits a level lower.
- A "change" that the GM agrees makes more sense than its lack is free. This can be construed as a clarification instead of a change, even if the GM wouldn't've thought of it; GMs make mistakes too. Suggesting changes is free, of course, but the GM may just say "no" to suggestions.
- A minor change costs 1pt. Such a change doesn't cause any dissonance, doesn't raise any questions like "If they're using the weapon here, what's the rest of the facility for?". It has no spreading consequences outside the scene. In general, it doesn't make more work for the GM. Often, such a change would seem pointless except for its match to the PCs's circumstances.
- A moderate change costs 2pt. It's a believable coincidence or addition, comparable to Serendipity. If it causes any dissonance, that can be resolved by ordinary coincidences elsewhere. It can lastingly create an NPC who you can take as an Ally or Contact between sessions.
- A major change costs 3pt. It's plausible, certainly possible, but surprising. It indicates that something strange happened here. It causes dissonance that can only be resolved if the NPC who hired you was lying, if the villain is playing a heretofore-unmentioned larger game, or the like.
- If you roll a crit and specify player guidance as the crit result, you get an extra level, to a max of major. If a single failed roll can prevent you from exploiting it(for example, the building exists, but you need a Stealth roll to get there ahead of your enemy), that's another way to get an extra level. If both apply, you can upgrade a single point into a major change!
After you suffer an attack, 1pt will reduce the injury to 1. Note that a single attack can contain multiple shots, and that this reduces injury, not damage, and not status effects that result from the injury(stunning, crippling, unconsciousness, death, etc). Other miraculous recoveries are possible, but should not be a routine use of karma points; talk to the GM.