"Spin-off" sounds about right.
Aimed at biking aficionados (and aficionadas - you can fiddle with the rider's leather you know), Tourist Trophy is meant as a counterpoint to Polyphony Digital's exhaustive Gran Turismo series. The set-up is immediately familiar - a series of "licence tests" to familiarise yourself with the concepts, a garage area where you can house and tune all the bikes you've acquired, and an enormous range of races in a variety of locations. The idea is to reapply Polyphony's renowned attention to detail, and biking fans sick of lightweight simulators are understandably excited.
They may very well enjoy themselves. Compared to MotoGP - one of the most celebrated series around - it's vicious. MotoGP knocks you over quite a lot, but you can generally see why you went over. Maybe you've gone too fast into a corner, or you're going too fast across the gravel, or you're powersliding a bit longer than you should be, or you're driving into somebody doing a handstand - that sort of thing. It's frustrating, but you know what you did wrong. Tourist Trophy doesn't care whether you understand why you've fallen over. It slaps you on the wrist every time you try to let your hair down. Make no mistake - this is a game where concentration is a must, and without the requisite biking experience only the dedicated need apply.
And while those of you who've been waiting for this sort of challenge can happily run off and buy it, the rest of us are left here wondering what the hell to make of it. For us, it exposes the flaws in the GT concept at every turn. And Tourist Trophy isn't without its own problems either.