One of the things that I find really defines a lot of games: Boss battles. After you've gone through the trouble of storming the castle, taking down the seemingly endless waves of cannon fodder, and jumping through all the bladed, flaming hoops, you'd better have the experience capped off with a memorable showdown with the local Big Bad... Though those first parts sound pretty awesome themselves.
But anyway, few things can sour my mood faster than an anticlimactic boss battle. (I'm looking at YOU, Gradius!) So, readers, what do you love and hate about boss battles? Here's some of my thoughts:
Big Peeve #1: Playing Tennis with the Boss: You know, where he fires some shot at you, you bounce it back, and so on until it hits him and renders him vulnerable. The first time I did it in Zelda: Link to the Past, I thought it was innovative. Now it's just tedious.
Big Peeve #2: Bullfight Boss: Only works for intro bosses who are obviously nonsentient. If the Magnificent Bastard Chessmaster final boss drops to this animal intelligence when he charges around all scaled up in dragon form, it kind of ruins my suspension of disbelief.
Bonus Point #1: Make me hate the boss. Emotional investment in defeating him tends to help me out for some reason.
Bonus Point #2: If you can successfully fool me with a "He was Right There All Along," you're doing something right.
Ablative Bosses: Don't know if there's a TV Tropes entry for this: Essentially bosses that peel off in layers as you fight them, changing in attack ability. I like the idea, especially for shmups.
Sequential Boss: This is one tradition that stuck and one that I hope stays stuck in regards to final bosses.
Tragic Monster: Very helpful for getting Bonus Point #1. Responsible for about 99% of my ability to beat the regular final boss rush in Cave Story.
Puzzle Bosses: As long as you put some thought into the puzzle bit. I like thinking my way through a battle.
Colossus Climb: I loved Shadow of the Colossus. Think I could have used some more active efforts at being knocked off, though.
Wake Up Call Boss: Set the tone fairly early, so that I'm not caught by surprise later.