Microsoft has kicked off the six-week promotion called ‘Must Have Games’ with, would you believe it, a Windows Phone exclusive - Hydro Thunder Go!

Hydro Thunder Go! is an eye-catching water racer based in the same universe as previous Hydro Thunder games (such as Hurricane on the Xbox Live Arcade), but comes with completely new tracks and craft to belt around in.

These craft are described as being ‘transformable’, although we suspect they mean ‘can deploy a massive pair of rocket boosters’ rather than ‘turns into a giant tapedeck'.

There are nine tracks in all, while unlocks, achievements, and leaderboards should provide the racer with some replay value.

If you’re quick on the draw, and think your water racing skills are unmatched, you can also send through a friend request to either Hydro Mobile 1 or Hydro Mobile 2 and race against some of Pixelbite’s finest.

Only the first 100 requests are accepted (naturally, as that’s still the silly friend limit on Xbox Live) so, as we say, you’ll have to be speedy.

Other games due in the ‘Must Have’ promotion include the ‘A lot of people already have’ Plants vs. Zombies and the ‘already have, surely’ Angry Birds.

Keep your eyes peeled to the Zune Marketplace over the next month and a half for those.