Gravity's plot is laden with doom. you are what's left of the human race, dedicated to setting up colonies and making money. This wouldn't be so hard if it were not for the aliens. You need stars to warm your planets, and they're going to turn the very same stars into big black holes.
Most of the time is spent zooming round in one of your space craft while the rest of the fleet wait to receive orders from you. Occasionally you encounter the odd alien ship, which, to start with, will be superior to yours. But as colonies grow technologically they provide you with both revenue and upgrades for your ship.
Most of the planets need life support systems. These are provided by programmed probes. If a rock is wholly inhospitable you can use - albeit at cost - the Genesis device (a la Star Trek) which can make anything inhabitable.
Even when a colony has been established there's still the threat of aliens wiping oft the sun, so need to keep a constant eye on all your star systems. Though the aliens appear not to discriminate beetween systems, it always seems to be one of your that ends up in darkness.
Rather than the usual bland 2D starfield, Gravity uses vector lines. These mark out gravity fields, and by traciking on eyou can get from A to B without using engines. Gravity is at its densest around black holes, where the vectors literally drop out the bottom of the screens. It's a very neat touch when you pop into a hole and reappear a trillion or more miles from the entry point (and it's the only convenient from of interstellar travel). and neat is a word which sums up this game. It borrows the best from a host of other titles, it's got a random element which does add variety, it's both complex and it's hard to define - yet it's all of this that makes it such fun. Once more, imageworks have come up trumps with an interesting, quirky game. Gravity i a great new release - it has got to be a must for the thinking games player.