Hades said:
I think we all had a game where the encounter with one of the bosses and us go ''wow''.
Either the boss was hard as hell, was fun to fight against, had awesome stuff happen on the background, a good soundtrack or you finally get to crush that villain that has been terrorising the heroes throughout the game.
So what do you think is the most important factor in a boss fight that just blows you away?
You mentionned it all. I'll just add that I think the boss should not be too "hard" either. It depends on the kind of game and the purpose of the boss but, unless the boss should feel like this, the fight shouldn't feel like you can't win otherwise it just becomes tedious and frustrating and your eventual victory becomes more of a "wow, glad I'm done with that" rather than a "wow, I want to play the game again just for that moment !".
Generally instead of a difficult fight I think it is better to have the boss looking difficult. For that the best way is to have one or several "tricks" to understand to beat it, so that someone who know it and practiced it can consistently beat it while still requiring the player to use different approaches to the fight.
For example, what made me remember boss fights in old games like R-Type or Ghost'n'Goblins was the attack patterns.
As for what is the most important to me, again, I'd say it depends on the game. In an RPG, for example, I'll want the bosses to be more than just "big enemy block path kill" so a good introduction, even if it is a non-sentinent monster/robot, giving them a bit of "character" developpement to tell the player why they should care for it more.
In more "action driven" games, as said earlier, a few good tricks. If the boss feels impossible to beat at first and then I notice that I have to aim for this part or that I can use this or that piece of scenery or simply that its attacks are avoidable if I learn the cues.
But, no matter the kind of game, I usually notice the soundtrack first. Not saying it is the most important thing, it's just one of the element and, as much as the others, it can make or break a boss fight.
Not all boss fight need a good music to become memorable. But it can really add to the atmosphere of the fight and make you feel "here".