Four Against Darkness

Solitaire Dungeon Delving
With a name that sounds a bit like a popular sword & sorcery story title (Two Sought Adventure by Fritz Leiber), Four Against Darkness is a solitaire dungeon delver where you control four characters. There are eight "classic" characters to choose from: warrior, wizard, rogue, halfling, dwarf, barbarian, cleric, and elf - each with its own specialization in one aspect of adventuring. The game supports a hack-n-slash style of play and can also be used for cooperative group play with each player controlling one or more characters.
Mechanics are built around the use of one or two six sided dice rolls. The dungeon is randomly generated in the basic game using a series of d6 rolls on various interlocked tables following a decision chart, but the system itself is robust enough to support story-based adventure and there are supplements (I have four) that offer additional characters and alternate adventure scenarios to replace the exploration of a random dungeon. In fact, all the pieces are there for it and I could see using Four Against Darkness as a rules lite refereed system.
The characters are all about class...they have no ability scores such as Strength, Dexterity, or Intelligence...they do level up, and level is added to a die roll for most tests. Each class is equipped to play their unique role in the dungeon so they can form a balanced party. The warrior is best at fighting, the cleric can heal, the wizard casts fireballs and the rogue removes traps. All the basic RPG stuff is here and it is all pretty standard if a bit sparse.
Rolling six siders to give the entrance layout to the dungeon from a table and any encounters which may occur there is how the basic game starts. Combat involves characters attacking by rolling a d6 and parrying by rolling a d6 comparing each adjusted result to the monster level. treasures, traps, quests and more await discovery on a number of d6 tables. Additional dungeon rooms are generated rolling d66 (two different colored six sided dice read as a tens and a ones die to give values from 11 to 66).
Four Against The Abyss takes the game to the next level(s). Once Four Against Darkness characters reach 5th level, The Abyss offers a new tier of play (through level 9) with more powerful spells and monsters and introduces the use of a d8 for combat and saves and additional rules for madness, hirelings and campaign plots adding variety and richness to the game experience.