This book constitutes the proceedings of the First Joint International Conference on Serious Games, JCSG 2015, held in Huddersfield, UK, in June 2015. This conference bundles the activities of the International Conference on Serious Games Development and Applications, SGDA, and the Conference on Serious Games, GameDays. The total of 12 full papers and 5 short papers was carefully reviewed and selected from 31 submissions. The book also contains one full invited talk. The papers were organized in topical sections named: games for health; games for learning; games for other purposes; game design and development; and poster and demo papers.