Regeneration

"For millennia, all that doctors could do to resolve traumatic injury was to remove foreign matter and patch the person back together. With the arrival of nanotechnology, we could do more than just wait for the body to heal, we could make the body heal directly." --Raphael-3000 
"Deadpool levels low. Must regenerate." --Deadpool, probablyRegeneration (varying costs) is a category of exotic physical advantages described in Basic Set: Characters pg 80 with specified names, listed under Cost below. "Regeneration includes Rapid Healing".
==Cost==
Its cost is based on how fast HP is recovered in addition to normal healing:
* Regeneration (Slow) [10]: 1 HP every 12 hours 
* Regeneration (Regular) [25]: 1 HP per hour
* Regeneration (Fast) [50]: 1 HP per minute
* Regeneration (Very Fast)/Classic Regeneration (Instant) [100]: 1 HP per second
* Regeneration (Extreme) [150]: 10 HP per second
==Special Enhancement==
*Fatigue Recovery (+100%): Only for Fast or better Regeneration.
*Heals Radiation (+40%)
*Heals FP Only or Heals FP or Heals Fatigue Only +0%
*Restores either FP or HP +20% (similar to Alternative Abilities)
==Special Limitations==
*Fatigue Only (+0%)
*Limited (-40%): HP is usually not restored but an advantage's recovery is accelerated
*Radiation Only (-60%)
==Regeneration and Very Rapid Healing==
All forms of Regeneration have Rapid Healing built-in (effectively eliminating Rapid Healing's roll) but given the first level of regeneration for 10 points restores 1 HP per 12 hours (2 HP per 24) while Very Rapid Healing needs a successful HT+5 roll.
This begs question of why take VRH instead of Regen 1.
The main reason is that Regen is exotic while VRH is mundane, so an 'origin' does not need to be declared for VRH and normal humans can get it.
Since Rapid Healing is part of Regen barring certain limitations there should not be a situation where VRH does something Regen cannot - it is a total non sequitur.
==Duration==
Regeneration seems like an "Always On" ability at first, but there appears to be another way to interpret that.
Bio-Tech pg 166 applies a Nuisance Effect to regeneration described "sweat heavily while regenerating" which is the only listed modifier, meaning that it otherwise operates under normal parameters.
The effect (-1 to reactions when healing) is priced the same (-5%) as it would be to get a Temporary Disadvantage worth -5 on a switchable ability, basically B22 Odious Personal Habits.
This implies that Regeneration must be switchable by default.
Clearly not the default "takes a ready maneuver" as if one took that enhancement on an always-on ability though, since Regeneration does not require a maneuver to turn on.
Regeneration as written is automatic, meaning it doesn't even take conscious input (like a Free Action) to turn on: it is essentially Reflexive (turns itself on when you are hurt)
Reflexive abilities can normally be voluntarily turned off. There's no indication that Regeneration works this way by default, so it probably comes with a built-in Minimum Duration.
Instead of a fixed number of seconds it would instead be "however many seconds it took to get to full HP".
There would also be some kind of terminating condition so the ability turned itself off (the bio-tech ceases to sweat) when it's no longer useful.
*Maximum Duration would not fit that since there's no 5 minute downtime
The inability to control the minimum or maximum duration could be seen as the ability being among the class of Transient abilities
P153's "the user must trigger" not applying due to Reflexive operation.
It can't operate like Uncontrollable or Unconscious Only since those allow Will rolls to turn off the ability, and it's not possible to turn off Regeneration unless it's switchable, either with the Switchable enhancement or something else which turns it off when a condition is not fulfilled, such as Costs Fatigue or Trigger.
A simpler approach could just be to require Switchable be bought to allow such things as Nuisance Effects to be turned off. Nuisance Effects were not designed to apply 100% of the time, but as temporary things.
A similar comparison is "Temporary Disadvantages" for Leech under Psychic Vampirism, the only known example of TD being applied to an attack: where the attack takes 1 minute to activate and the TD applies during the extra Concentrate maneuvers needed to activate it.
*this would not be that big a drawback for shorter activation times, temporary disadvantages that only last 1 second per use of ability are less inconvenient than ones that last 60 seconds per use of ability
==Activation limitation comparisons==
An injury trigger is a natural compliment for fast regeneration, but is largely pointless for slow regeneration, since 1 HP of injury must be suffered for 1 minute of activity. The -15% that's worth is a bigger discount than the -10% for Costs Hit points because it actually requires an action to injure (1 attack spent per minute) and the ability itself does not inherently injure the user as a free action.
Costs 2 HP -20% is also a superior discount and only costs 1 HP/min longterm after the initial 2 HP investment.
==Alternatives==
*Regrowth
*Healing
==Other Versions==
Hellboy Sourcebook and Roleplaying Game had 1 HP / 10 min for 35 points.
NineDaysDead suggested in 2006 that 1 HP / 10 sec should cost 70 based on prior patterns.
*His 2007 reply implies regeneration does not take place until your turn, but Absorption healing somehow does
Note that Takes Extra Time or Reduced Time could also be used, except it could never reduce to 0.
==Martial==
GURPS Martial Arts pg 47 discusses taking Limited, Crushing or Limited, Unarmed on it, similar to Damage Resistance.
==quotes==
===PK===
2009 http://forums.sjgames.com/showpost.php?p=864814&postcount=27 in respect to Regeneration
My house rule for Costs Fatigue takes this into account. If you have Instant Regeneration, the value of Costs Fatigue is reduced to 1/5. With Extreme Regeneration, it's 1/10.
But this is nothing more than the old, "A limitation that doesn't really limit the power is not a limitation." All I'm doing above is turning Costs Fatigue into a leveled Nuisance Effect, really, which is what it becomes if you recover FP that quickly.
===Kromm===
March 2011
:To qualify for Special Recharge, the Energy Reserve must require external charging, which means "external from the user."
:The usual methods of gathering energy from outside are DR (Absorption) and Leech, and spells such as Steal Energy. 
:With an Accessibility limitation such as "Only during mass" or "Only in a nuclear reactor," suitably modified Regeneration also counts. 
:Regeneration without such a limitation does not count, as there's nothing "special" about the recharge – it effectively comes from within. 
26 May 2017 Bruno said that Kromm suggested Reduced Time for both Weakness and Regeneration:
:Q: If it did then I could be taking Reduced Time to speed up the time it takes to recover points from Regeneration!
:A: Kromm has suggested that if you want levels past 10/second. Also for if you want a Weakness worse than 1d/minute.
==References==
*Basic Set pg 80
*GURPS Powers pg 70
Category:Advantages
Category:Exotic Traits
Category:Physical Traits
Category:Special Modifiers