ET Headquarters adds a flexible character customization system to Wolfenstein Enemy Territory. It also adds gameplay changes and rebalances class mechanics. Its core gameplay remains close to vanilla ET.
Blue adrenaline gives you speed only. It is a more milder version of red adrenaline. Class distribution is: engineer gets red, all the rest gets blue. This is also part of the rebalance of classes and should hopefully make the medic a bit less powerful, as red was given to him by default in vanilla et. Also the visuals are rewored. It now blinks red or blue, and inside the sprintbar as well.