Dead Island Definitive Edition

For this achievement all you have to do is kill 100 zombies (walkers, infected, and so on) with rage attacks. Getting kills will increase your rage-bar and once its completely filled you're able to change into rage-mode. Press the "B" button to activate your rage-mode. Once it has been started, almost every enemy will be a one hit kill, so you can wipe out many enemies at once. It usually does not take very long until its filled up again. To get the amount of rage you need for fury attacks faster you can unlock a few perks (the left skill-tree) which make you gain more rage by killing zombies.

You don't really have to go for this on purpose since it will unlock pretty early in the game (100 rage kills are not that much to be honest).