From WarzoneWiki

Units:

All mobile units except projectile in Warzone uses Collision Radius(also aka Circular Collision) to test whether 2 objects are bumped into each other or not,like most other RTS games do.

Projectiles:

All projectiles in Warzone are 'real' projectiles with bounding box,though the collision detection is different between branch and trunk:

• 1.x.x and 2.0 branch: All projectiles except Homing ones have a hit DICE(0 to 100),basically your unit will get hit even if the projectile misses your unit both visually and physically when DICE value is smaller than the weapon's accurancy.Homing ones will home forever unless the target dies/it hits the target(using bounding box).

• trunk: All projectiles use bounding box to test collision and the hit DICE only affects the missed vector x,y length and whether to use target-prediction when firing projectile.Also extended the lifespan of projectiles a bit,so the projectiles can travel a bit further if it misses its target.