Today I upgraded my Unity version and all my packages to support the newest Unity Physics (0.4.1) and Havok Physics (0.3.1). Before this, I was on Unity Physics 0.3 and Havok 0.2.2. I use Havok as my physics engine. Once imports completed and API's were fixed, I see now the physics of my game is wild different from before the upgrade. All the physics package upgrades I've done to this point has not changed how the physics of my game behaved until today. The change I'm experiencing is what I think to be related to how the physics react to impulses. My game has heavy reliance on PhysicsWorldExtensions.ApplyImpulse and the related to apply forces to objects (I apply impulse from force via I = F * ∆t). Every property of my game that utilizes impulses now acts differently. I scurried over every changelog I can think of including both physics packages. I could not find any entry stating any change in physics behavior regarding impulses, velocities, or just general behavior. Does anybody knows of any changes to the physics packages that has resulted in this change? Did the folks at Havok change some things internally to the simulation that now responds to velocity/impulse interactions different from before? Did simply the ApplyImpulse function change?