A few game tweaks before Steam Next Fest

Reduced time for first chaos level to 3 minutes, so rifts activate sooner.
Implemented left-click dragging within the mini-map so scrolling is easier.
Added a new 'rage storm' ability to swirling vortex troop that does bonus damage if target is at max rage level.
Fixed certain music tracks not playing entire track during Apocalypse phase.
Removed 'very easy' difficulty level for computer player.
Updated version to 2.1.1.12.