The Warlock of Firetop Mountain puts you in control of a wide variety of fighters as they work their way through the red-hued mountain. While each character has their own mission they wish to accomplish, they all have a secondary objective of finding the Warlock Zagor and defeating him, though why each character wishes to do this is different. Some characters are more virtuous than others, wishing simply to rid the land of Zagor's evil, while others will see it as a challenge to prove their own strength, and others have even less noble motivations. Like I said though, most, if not all characters, have other reasons to be in Firetop Mountain. Some are looking for specific artifacts, others are hunting beasts for one reason or another, but all have their own personality and traits which can have subtle changes in the way the game plays out for each character.
While the layout of Firetop Mountain is mostly static and you will find that the inhabitants of the caves are pretty well set, regardless of who you play as (with a few exceptions), the character you choose to play as can change how you interact with the world and the NPCs. Basic examples of this include a more daring character not wanting to sneak past some orcs, or another deciding to try and talk to an NPC instead of outright attacking him/her/it. Other differences come when your character finds some bit of information pertaining to their primary quest. If an NPC tells them directions to their goal, you will find many of your choices limited so that you are pushed in the right direction.
Outside of those variations though, the primary difference between each of the heroes comes down to their attacks when they get swept into a fight. Some characters will have more ranged attacks at their disposal, while others will deal more damage or cause additional effects when their attacks land. No character seems to be over-powered and are generally well-balanced, so it really comes down to learning the best way to fight as each of the heroes if you hope to progress in The Warlock of Firetop Mountain and see the missions to their end.
Firetop Mountain itself feels really big. The corridors are filled with branching paths and rooms that tease you with a variety of exploration options, but be warned; choosing a branch can often leave you forced in that direction. There are remarkably few times when you are able to backtrack and choose a different option, and those are typically the result of finding a dead end. What it has in abundance though is enemies to fight.
Each fight puts you and your enemies on a grid that represents the fighting area. Your character has a set list of attacks that can affect specific squares around them. In each turn, you can choose to either move or attack, the same choices your enemies have. The fights are all about tactics and judging what your enemies will do in the next move. If you attack the square they will be in without also getting attacked, then they take Stamina damage, but the opposite is also true. If the two of you manage to attack each other, then a roll of the virtual dice decides which character gets how much damage. The fight is over when either you are out of Stamina or when you've vanquished all of the enemies. Your reward for surviving a fight, besides progressing in the story, comes in the form of Souls which are used to unlock heroes.