There's an old game whose name escapes my aged brain, maybe Death Chase, in which you race through a forest on your bike trying to miss the trees and hit anything else that gets in your way. The reason I can't remember the name is that it came out about two years ago, and Sky Runner is really nothing but a tarted-up version of that.
Addiction is addiction, though, and even the simplest of games can keep you coming back for more if they've got the infamous Grab Factor. Sky Runner takes place in the latter part of the 24th century. The game starts with you in charge of a Skimmer, and astonishingly enough, this skims over the surface of a planet at just above tree height, while you have to shoot down the defence towers that look like telegraph poles.
Clear the first section of towers and the first of your three Skybikers descends from the Skimmer craft. These can now race across the surface looking out for other bikes, which may be friend or foe, so make sure you know whether you're meant to be taking them out or not.
Take out the last biker and you then have a crack at the huge Sky Harvester, and a map on the screen will point you in the right direction for that. Wipe that out and you go back again for more.
There are eight Skill levels, although they're called Threat Levels to make it all sound a bit more exciting, and instead of a score you have a cash balance, which you increase by eliminating everything that needs eliminating. The games quite addictive, but if you can take out the Sky Harvester on Threat Level 4 at your first attempt it doesn't sound too good for a long-term challenge.