The si is an artifact found on D:8. It is an unique item in that it has no obvious use as a weapon or tool, but will replicate itself over time. It is not clear what sis are, or look like, or why they are listed among "tools", though a successful Metallurgy check reveals they are made of adamantium. Being artifacts, they cannot be used for smithing, however.
The si is considered quite desirable in the early game, since it serves as a source of income: the newly generated sis can be sold ad infinitum to shopkeepers for a fairly substantial price. They can be thrown as missiles with some minimal effectiveness, and can be used as a placeholder in the inventory to prevent dooming while dealing with a hostile altar. Later in the game they are often considered a nuisance because eventually the weight of many sis will start to encumber the PC. They are particularly problematic in the Infinite Dungeon, since the sis will automatically return to your inventory when ascending or descending, meaning there is no way to shed the extra weight of the heap of artifacts (it is also possible to be crushed in this way). Note also that unlike most other artifacts, sis cannot be given to the Demented Ratling.
They can also be wielded as a weapon to bash monsters that would otherwise damage weapons, although the fact that having acid resistance prevents these monsters from damaging any gloves or gauntlets usually offers the better option of fighting unarmed.
The first si is found lying on top of a trap on D:8. Subsequent sis are generated through replication.
The rate of growth of sis seems to be based on their blessed/uncursed/cursed status. A simple test of a PC with a single si in his inventory waiting for periods of 1000 turns reveals that, on average, a single cursed si will grow into 1.7 sis every 1000 turns, a blessed si will grow into 2.2 sis every 1000 turns, and an uncursed si will grow into 1.3 sis every 1000 turns. Of the newly generated sis, the test suggests that 82.5% will be uncursed, 4.7% will be blessed, and 12.7% will be cursed. Note that since each newly generated si in turn replicate into further sis, the overall rate of si growth will be exponential in nature.
Greater Identify informationEdit
------------------------------------ si ------------------------------------ Weight: 10s The strange item is really an uncursed si. When used in melee combat it grants a +0 bonus to hit and causes 1d4 points of damage. When used as a missile it grants a -4 bonus to hit and causes 1d4 points of damage.
Source: Andy Williams' ADOM Guidebook
The readme file for the game gives the origin of the fabled si:
If you are interested in how it got into the game, here we go: Quite a number of years ago (that must have been around 1985 or so) I played a lot of AD&D with a friend. We had two characters, dwarven fighter/thieves of LN alignment named Gorko Galgenstrick and Groron Garman respectively, who lived through many many adventures. One day my friend looked at the character sheet of his character, Groron Garman, and discovered garbled writing in his list of normal items stating that he owned a "Si". We had no idea what that could be and how it got there and we were pretty puzzled but left it that way, making occasional comments about Groron's mighty artifact, the Si. Months later my friend again was revising the list of normal items his character lugged around and noticed the word "Si" in a second place on the equipment list. Now we were really puzzled and declared this item to be an artifact with unknown powers. The 'Si' in ADOM is just a kind of insider joke on my behalf to celebrate those great old days :-)