Invaders have a 'sickness' and when they get within 6 range of a creep the sickness can spread to that creep. Tough parts can reduce the chance of getting the 'Invader flu'. The creeps TTL will drop quicker and can spread the sickness to others. When a creep with the sickness dies you get negative points.
Each region of the map needs to collect/deposit heal boost into a central 'lab'. After enough boost is collected the lab will create a 'cure' You then need to boost a heal creeps with the 'cure' boost. Healing creeps while boosted with the cure creeps will give you points.
The sector with the highest points wins.
As if we haven't had enough of this