Sanctity

Sanctity is a cancelled Mac game by AntennaHead Industries. It was to be an arena shooter.

Plot
A mysterious zone materializes over some Pacific islands. Aircraft and boats that enter this region disappear. You play as an elite military member tasked to stop whatever is causing this phenomena.

Gameplay
Combat would be third-person dogfiting in huge areas. You could control planes, tanks, boats, truciks, motorcycles, and even sheep.

Cancellation
Sanctity was cancelled when AntennaHead Industries went defunct around 1999-2000. The shareware demo of Shatterbat has a preview of Sanctity.

Video
https://www.youtube.com/watch?v=v73QRAJ0GK0