Like I said earlier,
Roadkill takes place in the future where most of the world's population has been killed by a virus called 'The Rot', and those who have survived are either members of brutal gangs, or people just trying to live another day. You are a lone wolf named Mason Strong and you are traveling to a place known as Paradise City - a pristine place that doesn't appear to have been touched by the disease that has forced the world into chaos. Of course, there are also gangs fighting over control of this city as well.
Mason is on his way to Paradise City, not for the glory of the city but for revenge -- cold, hard revenge. You see, years ago Mason had worked his way up in the ranks of one of the Paradise City gangs. Eventually the leader of this gang didn't like all the questions Mason was asking, so he left our hero for dead in Python Canyon -- but now he is back and doing everything in his power to take down the leader of his old gang.
Along the way, you will travel through Lava Falls and Blister Canyon. While there, you will work for local gangs, unlock many vehicles and buy upgrades for these vehicles. Each vehicle has a primary weapon - a machine gun, but you can buy upgrades and additional armor at the shop with the money you collect by picking up scrap from other fragged vehicles.
Most of the time, while employed by these gangs, you will have missions to run -- you know, kill this guy, destroy these objects, the basic stuff. But one of the best parts about this game is that you don't necessarily have to do these missions (well you do if you want to advance the story, but if you don't, then that's okay too). Many times, I got frustrated with a mission and instead of taking it up, I went on a killing spree destroying any vehicles and people I could (mostly because it took my mind off the fact that I wasn't able to do some little, annoying task in the last mission). Doing this typically paid off in a lot of scrap -- thus a lot of money and upgrades for my vehicle.
Mind you though, you won't have to go to the shop for every upgrade. There are various boxes throughout each level -- each contains part of a vehicle or a weapon. Collect all four boxes and the object's corresponding blueprint and you have yourself a new weapon or vehicle at your disposal.
There is also a Deathmatch Mode available where you can go head-to-head against up to three other vehicles in an attempt to get the most kills the fastest. There are five power ups on the field as you ride the roads in search of your next victim. These bonuses will increase your firepower, allow you to fire twice as many shots in a given amount of time, turn invisible, increase you armor or add a wingman to your turret gun.