Grendel is a mean and nasty AI monster and at times he seems intelligent and as if he has a mind of his own. His goal is to harass the players of Grendel's Cave as much as possible. He stalks you, mangles or takes your stuff, chases you, and attacks and kills you without mercy. During the day, he will not come outside of the cave and he mostly sleeps, but at night, he is active and comes out to find his prey. He kills sleeping thanes in Heorot Hall and visits the Dragon to replenish the treasure. He is stinky and you can smell him coming. The closer he gets the more he stinks. If you smell Grendel coming for you, you should create a new thane and feed him to Grendel. Once Grendel eats, he will run back into his cave and hide. This gives you time to play without him harassing you.

The goal of Grendel's Cave is to kill Grendel. This is no easy task, because weapons cannot harm Grendel and you must be carrying Yggdrasil to kill him. Do not attempt to attack him without this amulet. You obtain Yggdrasil by trading a collection of other amulets for it. There are twenty-three different amulets, each associated with a Quest, and each kingdom type requires a different amount of amulets for the Yggdrasil trade. The easier the kingdom the lower the number of amulets needed. Please read the Quest section for more information on how to obtain amulets, so you can kill Grendel and win the game.