There are 15 achievements tracked for GnollHack in the Junethack tournament.
ascended
entered Astral Plane
entered Elemental Planes
obtained the Amulet of Yendor
performed the Invocation Ritual
obtained the Book of the Dead
obtained the Bell of Opening
obtained the Candelabrum of Invocation
entered Gehennom
defeated Medusa
obtained the luckstone from the Mines
obtained the Sokoban Prize
escaped in celestial disgrace
killed Yacc
touched the Prime Codex