Could use a couple of extra speed settings. Toward the end of the game, when you're just waiting for people to die off or to gain points towards upgrades, it can get a little boring. Other than that, love it, 4/5.
Got the extreme badge :D For those having trouble, set up a nuke (Rockets + Machine Gun + Machine Gun), once you unlock the Rate+ and Damage+ bonuses, stick some of them with it. To keep the enemies all in one place, a couple of Tazers near the entrance (Within combo distance) will slow them down. Just make sure to max out the damage and rate.
Absolutely loved this! Art style was fantastic, the various routes were a brilliant touch, awesome set-pieces. If there was a multiplayer race-mode on this I'd be all set to explode in my pants.