Other pages already discuss Insanity, but from the point of view of a magic rich campaign. A better way of approaching it might be to define Insanity from a more realistic viewpoint, then add the magic hooks in later. This allows us to use it in a Horror setting.
In game terms, Insanity is a measure of how much control the player has lost over their character. A truly insane character may be unplayable, or at least forced to play in a certain way.
Insanity ranges from 0 (sane, whatever that means), through 1 (very mild) to 5 (totally insane). A character with level 5 insanity is unplayable, and cannot function as an intelligent being. The table on the Insanity page is still applicable:
| Insanity | Description |
|---|---|
| 0 | Totally sane. Most of the population. |
| 1 | Mild insanity. Has very little effect on the character. |
| 2 | Moderate insanity. Effects the character in little ways. |
| 3 | High insanity. People will recognise the character as odd very quickly. |
| 4 | Severe insanity. The character cannot function in normal society. |
| 5 | Critical. The character has lost all their humanity. |
Will is used to retain sanity. When making tests to retain control, Insanity reduces your Will. It may be possible to end up with effectively negative will.