When I was playing dying light with friend we discovered that every timw you go to sleep and wake up air drop will appear, if you don’t know air drops are pretty rare and if you collext them and deliver to one guy you will recieve lots of xp, we used that multiple times to unlock grapling hook very early. Air drops also gave lots of medicine which was hard to get in early game and that very helped us
The games stacking effects were so broken I remember you could stack your acrobatics enough using potions and equipment that I was able to jump on one side of the map and literally fly all the way across to the other side before landing