Wikipedia
Lexicant
Lexicant is a paper and pencil word game for two players. A letter is written on a sheet of paper, and each player takes turns adding a letter either to the beginning or the end of this ever-growing word stem. Any word-stem a player creates must form part of a valid English word, without actually being a word itself. The first player to create a word (with at least three or four letters) loses.
Lexicant is popular because of its inherent simplicity. It requires no preparation, and can be played with paper and pencil or simply spoken aloud.