There are two circles in front of you: Circle A and Circle B. One of them is soft. One isn't. One of them is heavy. One isn't. One of them is painted. One isn't, and so forth. And the question you must answer, in this puzzle game by Yoshio Ishii, is simple: Which? It's very much a mouse driven game, and players will have to point, click, drag, drop, spin, launch, rub, and slide to tell the difference in all twenty levels. Figuring out the challenges will depend less on logic, and more on playful experimentation to determine what the developer had in mind. This can be occasionally frustrating, but all of the levels are quite clever, and have an impish streak of fourth-wall aware humor. In short, Which? is a quality five minutes of fun, that fans of Ishii's Hoshi Saga and spin-offs will find very enjoyable.