8 hours, junk mechanics.
Spawn process no longer allows for spawners to overlap one another when spawning in at the same time. Toppling flier spawner junk does damage now. Walker spawner junk waits for the player to clear out from under it before collapsing (likely will tune this to be a capped waiting period). Pick ups that get hit by the kill colliders on moving junk are teleported above the junk to prevent them from being tapped in unreachable locations. Junk lasts a certain number of phases (temp fix). Solving the problem of the player standing on junk to escape walkers in early phases by making junk that is touched by walkers deal 50% health damage to the player for every 2 seconds it is in contact with walkers.