SLethe is a short name for the port of the Lethe patch to SLASH'EM. The patch is against SLASH'EM 0.0.7E7F2, a version which already contains parts of the Lethe patch. The name SLethe can also refer specifically the 0.0.7E7F2 playground at slashem.crash-override.net that uses this patch, or the playground at em.slashem.me that also uses this patch, or to the Rodney (bot) clone that reports deaths from this playground to IRC #slashem at Freenode.
SLethe adds several new levels, the Lethe river and three new objects; the patch drastically replaces the old Gehennom of mazes and lairs with a new, mostly fixed-layout hazard. However, the patch does not add new monsters, because SLASH'EM 0.0.7E7F2 already contains the Lethe monsters, even Cthulhu.
Michael Clarke created the original Lethe patch for NetHack 3.3.1. In 2002, the SLASH'EM project began to merge the Lethe patch into SLASH'EM. Darshan Shaligram did much of the initial porting work. A question arose about how to integrate the new Lethe levels into SLASH'EM. (Threads from the slashem-devel mailing list are Some questions on Lethe and Dungeon reorganization - shades of Lethe.) As a result, the release of SLASH'EM 0.0.7 contains the new monsters from the Lethe patch, but not the new levels. (Forum thread is Lethe.)
Then Marcin Kościelnicki ported the remainder of the Lethe patch to SLASH'EM. This patch is SLethe 1.1. (Rgrn thread is Slashem & lethe.) This patch is a context diff, against SLASH'EM 0.0.7E7. Fetch the patch from http://markosc.w.interia.pl/Slethe-1.1.patch. Note that a context diff is more difficult to read than a unified diff.
The playground running at slashem.crash-override.net and em.slashem.me is SLethe 1.5. This is a context diff against SLASH'EM 0.0.7E7F2. There is a copy of SLethe 1.5 at http://bhaak.net/nethack/Slethe-1.5.patch. This patch is difficult to apply because extra copies of objnam.c.orig and zap.c.orig are in the patch; these conflict with the backups that the patch command makes when you apply the patch.
Changes made by this patch
Warning! The content of this section is a result of reading the patch, and does not represent actual experience playing in these levels.
- Starting below Medusa's Island, some levels now contain lethe water that causes amnesia. Do not step or swim in this water.
- The Lethe Gorge is the dungeon branch immediately below Medusa. It contains the nine levels, all of fixed layout, with the Castle on the third level and the stair to the Valley of the Dead (Gehennom) on the ninth level. Some levels specialise in certain monsters, like ogres or undead.
- The Castle is now in the Lethe, so the moat contains Lethe water.
- The Castle also has extra towers on the side, so even if you cross above the water, you will not be able to go around to the back of the Castle. You can use the secret doors to enter the side of the castle.
- A second staircase down from the Castle leads to a wine cellar with many jellies, puddings, and green slimes.
- Gehennom is rearranged. Now 0.0.7E7F2 had the valley first, then demons, Wizard's Tower, and devils. The valley stays first, but the patch rearranges the lairs, mixing the demons and devils, putting easy Asmodeus before difficult Demogorgon.
- The Lethe reappears in the Valley of the Dead and again in all of the demon and devil lairs. Many lairs now fill the level, removing the random maze that once surrounded them.
- Gehennom also contains a Pleasant Valley; it includes several peaceful monsters but also a group of hostile opponents, though many of them are asleep. It also contains the entrance to Vlad's Tower.
- Above the sanctum are the levels of the Gulf of N'kai. Players should be ready to dig through walls and fight some of the new monsters. One level has a portal that leads outside Gehennom to the Wizard's Tower.
- Cthulhu's Sanctum! The sanctum is now a dangerous place with two drawbridges, eight unaligned temples, and plenty of squeaky boards to wake the deeper ones and deepest ones. Cthulhu himself stands in one of the temples with the Amulet of Yendor. If you kill him, then he reappears on the level.
- New weapon: silver capped staff belonging to quarterstaff group.
- New scrolls: scroll of demonology and scroll of elementalism, which you or a monster can use to summon & or E. If used carefully, then you might summon tame ones.
- New monsters.