Spoiler
0.10.2.1 Background corruption
As mentioned above, the PC must eventually enter areas where background corruption occurs. Areas with no corruption flag set:

* Small Cave before day 90
* Uninteresting Dungeon
* Dusty Dungeon lvls 1-2
* Village Dungeon
* Druid Dungeon
* Puppy Cave
* Caverns of Chaos lvls 1-9
* Infinite Dungeon lvls 1-9
* Wilderness
* Gremlin Cave
* Dwarven graveyard
* Water dragon cave
* Greater White Unicorn Glade
* Terinyo
* Lawenilothehl
* High Mountain Village
* Old Barbarian's Glade
* Mad Minstrel's clearing

Otherwise, the corruption points (CP's) gained depend on a Danger Level (DL) in particular area. Refer to section 0.13.15 for the list of areas and their DL's.

Thanks to Vladimir Panteleev for the following information.

No other corruption occurs if:

* the current level has the NoCorruption flag set (see the list above)
* DL < 10
* the chaos gate is closed.

The background corruption is applied once every N turns. If the PC is doomed, that's TWICE every N turns:

if (TurnNumber mod N=0) or (Doomed and (TurnNumber mod N=1)) then

(this is how mathematicians/programmers say once normally and twice with doomed intristics per N turns)

N is calculated based on the DL the PC is on.

* ID: N=CorruptionSpeed[ Max(Min(90,CurrentIDLevel)-10,0)/20 ]
* ID 67: N=20
* Levels with Danger Level>40: N=CorruptionSpeed[ (DangerLevel-5)/10 ]
* Other N=CorruptionSpeed[ (DangerLevel-10)/10 ]

CorruptionSpeed is a 5-element array

* CorruptionSpeed[0]=20
* CorruptionSpeed[1]=15
* CorruptionSpeed[2]=10
* CorruptionSpeed[3]= 5
* CorruptionSpeed[4]= 2

Put in words, N can be 2, 5, 10, 15 or 20. The smaller N, the faster the corruption. In the Infinite dungeon, N is 20 for levels 10-29, 15 for levels 30-49, 10 for levels 50-69, 5 for levels 70-89, and 2 for levels 90 and above. The exception is level I: 67 (the special level with MaLaKaI) where N is 20. For other areas, N is 20 for DL 10-19, 15 for DL 20-29, 10 for DL 30-39, 5 for DL 40-44, and 2 for DL 45 and above.

If the background corruption is to be applied on this turn:

* 1 CP is always applied
* if the current level is in the CoC and DL > 45, +2 CP
* chaos plane: +1d100 CP's
* emperor moloch's level: +1d33 CP's

Now, there's a bug in the corrupting code. This is how it SHOULD have worked.

* +1 CP if it's beyond day 90.
* +2 CP if it's beyond day 180. (cumulative with previous)
* +3 CP if it's beyond day 270. (cumulative with previous)
* +4 CP if it's beyond day 360. (cumulative with previous)

However, only the first line is executed - the 90-day limit.

Being L+ decreases corruption by -30%, L or LN -10 %, C- enhances corruption by +30%, lawful Unicorn-borns -10%, L50 farmers and lawful paladins -30%, L50 monks and druids -10%.
(See, it's not getting crowned that makes you get corrupted faster, C- alignment alone is enough. Beware, DE Necromancers! Also, let's see: Unicorn born L+ L50 farmer, 10+30+30=70% resistance to corruption. Not bad. -J.)

Note that since background corruption is applied only by 1-2 points, the above do not affect its speed, but major corruptions, such as eating chaotic corpses etc. The "crowned as champion" status does not affect corruption speed. By the way, 1 corruption = 1000 CP's.

Note that a corrupting level can be made less so, or even completely noncorrupting, by reading scrolls of peace. These reduce the danger level, and thus the corruption rate of the current level. Bless the scrolls before reading them. The number of scrolls required depends on the level. If Dwarftown is generated on D: 10 or D: 11, for instance, reading two blessed scrolls of peace will probably stop corruption. On the other hand, if it is necessary to stop corruption on a particular level of the blue dragon caves, approximately nine scrolls of peace are required.