Core Mechanic Edit
The core mechanic of Survivor System is a roll-high based dice mechanic. The GM will call for a skill roll of some kind, you will find that skill and add it's value to a 1d100 roll. So, if he asks for Engineering and you have 20 in the skill, you would roll one 100 sided die and add 20 to the result.
Character advancement takes two forms. These separate advancement tracks are designed to emphasize balance between the combat and non-combat aspects of the game.
The first, advancement through use, allows a player to improve a skill value by 1 whenever they succeed on a challenging skill roll. The more you perform a task, the better you get at it. This eliminates the arbitrary level based advancement of other popular systems, and the awkward situation where, due to experience from combat, a character gets better at cooking.
The second, advancement through combat, allows the player to choose a combat related ability after every 10 successful combat encounters. This allows players to be rewarded for success in combat, without building the entire advancement system around it or placing undue emphasis on violent confrontation.