Thief Deadly Shadows is the latest installment in a three part series, beginning in 1998 with Thief Dark Project, and following two years later with Thief Metal Age in 2000. It helps to have at least played a bit of Thief before, but it's not really necessarily. In any case, I highly recommend the other two Thief games as well (but this review isn't about those, so I won't really go into that further unless someone requests me to), if you can somehow find them for retail somewhere.