I am absolutely not the best person to ask about fitness games... as evidenced my fifteen stone bulk for my sub-six foot height. But as far as I can work out, Zumba is a crazy, dance-based workout that's sweeping the country's community centres - and has made the jump to consoles where motion control allows calories to be burned and counted.
I may not know fitness, but I do know sales data. Last week, Zumba Fitness beat Crysis 2 to the top of the UK charts. So there must be something in it.