One of my favourite finds at Rezzed was Exo One [official site] - a momentum-based planetary exploration game. You roll and fly across desolate spacescapes flipping form between a ball and a frisbee. The enjoyment comes from using the terrain and the controls in just the right way to go full speed. The best way I can think to describe it is like a 3D version of the mobile game, Tiny Wings.
The trailer is decent as giving you an idea for how the worlds look and what you might see if you look over someone's shoulder but it's not really able to convey how the game feels and that's where you find the real attraction. Y'see, the joy of it - at least when I played it - was in learning to read the terrain and working out what would give you speed boosts and exactly when to make your little spacecraft bear down on a slope to build momentum, then when to let go so it would use that momentum to zoom up an incline or perhaps into the air for you to turn it into a disc, skimming through clouds.
There's a real joy in moving at maximum speed which doesn't translate to trailers because of how dependent it is on knowing the sweet spots of the input system.
From what I played the tutorial isn't quite there yet, but I had so much fun whooshing about on the actual demo level! I'm actually sad at how fast I got to the big planetary laser thingummy I could see in the distance when I spawned because that shoots you off into space and off to a new location. I felt like it marked the point where the next person has a go on the demo. If I'd been smart I would have careened off in a different direction (because the game doesn't funnel or force you towards said laser if you want to play around a bit) and just treated the world as a kind of skate park!