ARM: Advanced Role-Playing Mechanics

From the introduction:

ARM is an adaptable generic RPG, designed by a minimalist author. This means that details are often left up to the GM and the players - I prefer that room for my imagination to work, and I dislike getting bogged down in complex rules.

User summary:

ARM uses a unique logarithmic resolution table to determine target difficulty. Character stats are also based on logarithmic values adjusted by situational modifiers and a die roll. This resolution process is used for everything in the game. The game is copyright but distributed freely and exists in ASCII text form only.