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
Borderlands 3, the mail duplication glitch, I felt awesome since it was something I discovered without looking at guides, couple of years later I found out it was a pretty common glitch, still cool tho