A sanity system

[RogerBW]

I like the death spiral of SAN loss in Call of Cthulhu, and I think it's something that standard GURPS fright checks don't simulate well. I'm also not terribly fond of the way GURPS Cthulhupunk did it. Hence this. Comments welcome.

The master copy at http://tekeli.li/gurps/sanity.html will be kept updated.

1 Basics

A character’s sanity is measured by his current Fright Check value: Willpower, modified by Fearfulness (p. B136) or Fearlessness (p. B55). When this value reaches 2, the character is unplayably insane.
Players using this system may wish to buy more levels of Fearlessness than usual, or even Unfazeable (p. B95). GMs may wish to allow a limited amount of Cosmic Fearlessness (3 points/level) and should not allow Cosmic Unfazeable.

2 Frightening Events

A normal frightening event is resolved by the normal rules for Fright Checks (p. B360), remembering the Rule of 14. Characters with Unfazeable remain immune to such events.
A frightening event of cosmic import — for example, seeing undeniable evidence of a creature that the PC knows should not exist, casting
spells, or reading certain books — provokes a Cosmic Fright Check. This has two significant differences from a conventional Fright Check:

• Normal (non-Cosmic) Fearlessness and Unfazeable give no benefit.
• If the PC has a Hidden Lore skill appropriate to the source of the terror (e.g. Cthulhu Mythos), perhaps at default, the Fright Check is penalised by the skill value minus 10 (minimum 0).

Any failed Cosmic Fright Check, in addition to the normal Fright Check Table results, reduces the PC’s Fearlessness by one level (reducing Cosmic Fearlessness first), or adds a level of Fearfulness if the PC had no Fearlessness.
As always, the results of the Fright Check Table should be interpreted appropriately for the situation. Depending on the situation, conventional fright check results in the 10+ range may also give a Fearlessness loss, at the GM’s discretion.

3 Recovery

PCs may spend earned character points on reducing Fearfulness or adding Fearlessness. This will normally involve intensive psychotherapy, and take approximately a month per level, during which the character should spend at least four hours per week in therapy.
GMs may choose to award “sanity levels”, points which may only be spent for this purpose.
A PC who has failed a Cosmic Fright Check may buy a Perk of immunity to that particular source of horror (e.g. “Deep Ones”).