Top Secret uses the Lucky 13 rule system, originally created by Solarian for Top Secret. The Lucky 13 system is available for independent game designers who would like to adapt it for use in their own creations. Information is available at https://solariangames.com/the-lucky-13-game-engine-is-free-to-use-in-your-own-game/
Lucky 13 is meant to be easy enough to learn in a couple of minutes, but support enough “crunch” to create a game where actions have predictable consequences, and choices matter.
At its heart, Lucky 13 relies on two kinds of rolls: skill checks and contests. A skill check happens anytime a character wants to use their training and abilities to do something that has a chance of failure. A contest happens anytime two or more characters are opposing each other, whether it’s physical combat, a battle of wills, a chase, or anything else.
The engine is called “Lucky 13” because skill checks always require a 13 to succeed.
The difficulty is raised or lowered by the size of the dice the player gets to use when trying to roll a 13.
Lucky 13 uses five dice during gameplay: d4, d6, d8, d10, and d12.
