This is an RPG mechanism used by Philippe Tromeur in a number of his one-page role-playing games. He developed the system in 2007 during which time the exact mechanics varied somewhat, and then used it often in 2008 in a fairly stable format.
The core system uses a short list of attributes. At character generation, players have a set number of points to distribute amongst these attributes.
Task resolution is performed by rolling a single twenty-sided die. Rolling less than or equal to the attribute is a success, and rolling more than the attribute is a failure. On top of this, rolling a natural 19 is always a failure, and rolling a natural 20 is a critical failure. Similarly, rolling a natural 2 is always a success, and rolling a natural 1 is a critical success. Further, any roll that is less than or equal to one-tenth of the attribute value (rounding up) is also a critical success.