The Team17 Softography Says...
This game is not listed on the Team17 Softography.
Dream17 says...
From the few leaked screenshots available, it looked as though Worms Battle Rally was set to be a vehicle-based battle game in a similar veign to Twisted Metal, or the Battle mode from the MarioKart games. Of course, the game might've also included an actual racing mode, but we'll never now now, eh?
Production on WBR was halted as part of the developer/publisher deal which resulted in Worms Forts: Under Siege.
Hmm... this looks pretty fun, actually. I wonder if Team17 will attempt something similar in the future?