Complex sentence: Besides an author of books on games, Pritchard was editor of "Games & Puzzles" magazine from 1972 to 1981, and subsequently editor of "The Gamer".
Split into simpler sentences: Besides an author of books on games, Pritchard was editor of "Games & Puzzles" magazine from 1972 to 1981. Subsequent to "Games & Puzzles" magazine he was editor of "The Gamer".