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
I remeber getting 1936 tanks from Bosnia in 1914 because of a bug in Hearts of iron 4 “Great War” mod. When the great War started while entente doesn’t even having a tank blueprint I was using tank divisions as Austria Hungary.