Releasing a game demo may not actually be a very good way to boost game sales; in fact, it could reduce the number of copies you shift by up to half.
That’s the claim made by industry analyst and Puzzle Clubhouse CEO Jesse Schell during a presentation at DICE 2013 (via PCGamesN), and he even had a graph to back him up.
Using Xbox 360 sales as an example, Schell proceeded to show his audience that the best-selling games were those that built expectations in players, but then gave them no way to try it out short of buying a copy. Summarising the collective feeling of the room, he said “You mean we spent all this money making a demo and getting it out there, and it cut our sales in half? Yes, that’s exactly what happened to you.”