Also the name of a Horror Role-Playing Game created by Mayfair Games in 1990, now sadly out of print.
The system is different from many Horror Roleplaying games, in that the PCs are simple ordinary people, with no magic powers (though they can eventually learn them) or superhuman abilities. They are also unlikely all to be soldiers or vigilantes. Indeed, the majority of players will be librarians, factory workers, scientists, shop workers or other ordinary, run-of-the-mill occupations. Players deciding to be an Army Veteran who happens to study the occult and ways of defeating evil monsters are not entering the spirit of the game.
The game is based on a percentile system. Each player has 8 stats: Strength, Agility, Dexterity, Stamina, Perception, Personality, Willpower and Luck. Most skill rolls are based on horrendously complicated mixtures of these stats, with a bonus for the level of the skill you have. There are three levels of skill knowledge: Student (+15), Teacher (+30) and Master (+50).
Chill is different to many similar games because the characters are not heroes. They are normal people. They rarely dispatch mighty demons from the Unknown. Most of the time, they run, and hide, and fear. the goal of the Game is not to win, but to survive for another few hours... and doing so requires skill, quick thinking and luck. Otherwise, you simply fail and die - if you're lucky.