It all comes down to... THIS!?
Reaper-Human Larva (Mass Effect 2)
The Pitch: "This is a true David-versus-Goliath matchup. It's Commander Shepard's first time going mano e mano with a Reaper. And not just any Reaper, a Reaper made out of liquified humans (some of which might even be his former crewmates). In the original Mass Effect you see a Reaper get taken down by the combined might of the galactic military. Now, you get to take one down yourself with the combined might of Shepard and her friends."
The Reality: It's a bargain-bin Terminator with a bad cough. What should have been the endcap on an excellent action set-piece ends up feeling wholly unnecessary due to its mediocrity. The classic one-two punch of squatting behind cover and shooting the weak spot is all it takes to put this baby to bed. Considering that everything leading up to the fight - the Collector battles, issuing life-or-death orders to teammates, dealing with the Illusive Man - has been amazing, Shepard and friends could have skipped this final bout.
The Joker (Batman: Arkham Asylum)
The Pitch: "We've seen the Joker scheme against Batman, send henchmen after Batman, and sometimes wail on Batman (and his loved ones) with a crowbar, but never have we seen him go toe-to-toe with the Dark Knight as equals. Forgot all the philosophical order-versus-chaos nonsense. Let's pump the Joker full of Titan and set this Hulked-out beast loose on the Bat."
The Reality: When he's not flailing around the arena like a three-year-old trying to hit a pinata, the Joker spends most of his fight showboating in the background as if this were a WWE pay-per-view event. Of course, this entire sequence is undercut by the fact that - at this point in the game - Batman has already faced Bane, Killer Croc, and several beefed-up mooks, so fighting another Big McLargeHuge isn't anything special.
Lambent Brumak (Gears of War 2)
The Pitch: "What's the most devastating weapon in Gears of War 2? That's right, the Hammer of Dawn. And the player gets to use it, what, like three or four times the entire game? That just doesn't seem right. For the final boss it's going to be all Hammer of Dawn all the time. Space lasers are going to be flying every which way as Marcus and Dom take down a giant mutated Godzilla monster whose death will trigger a blast the size of a WMD."
The Reality: The problem with basing an entire boss fight around the Hammer of Dawn is that the Hammer isn't all that interesting a weapon to use. It's basically a big laser pointer for a satellite cannon to target. Using it is about as exciting as an adventure game puzzle: use Hammer on Brumak for victory. It's really more of a spectacle than a boss fight, one that feels old before it even starts.
Nihilanth (Half-Life)
The Pitch: "In the distant reaches of time and space, Gordon Freeman stands alone against the Nihilanth, a bulbous and grotesque alien mastermind wielding strange and unusual magics. You are cut off from everything you've known. There's nothing left for you out in the void, save for this final battle, followed by certain doom. It's a suicide mission, but someone has to do it.
The Reality: Fighting this overgrown space baby is such a drag. All the creepy ambiance in the world can't make up for the fact that all you have to do is slowly circle around it while shooting its big, bulbous head. Its attacks are slow-moving and easy to avoid, save for one that will teleport you down a giant space well if it hits. You then have to climb back out by doing some of that oh-so-enjoyable late-90s first-person platforming everyone remembers so fondly.
Rodrigo Borgia (Assassin's Creed 2)
The Pitch: "It's the Pope. The freaking Pope. The magic-staff-wielding, drunk-with-power supervillain Pope, and YOU get to fight him using the mystical Apple of Eden. This is an insane crossroads of Catholic iconography and supernatural mumbo-jumbo built to serve as the backdrop for one of the most outlandish holy rumbles ever to transpire. One must assume that, when the Assassin's Creed series was created, it was with the intent of presenting this matchup."
The Reality: The street-level combat of Assassin's Creed simply doesn't lend itself to the grandeur of fighting His Holiness. Ezio and his crew of magically-conjured assassins encircle their target and take turns swatting at him as if he were a fly on a horse. It's about as interesting as it sounds. In stage two, all weapons and assassin ghosts are swapped for a good old-fashioned punch fight as you pummel a basically defenseless man into submission. Again, not exactly the heroic finale it could have been.
Solidus Snake (Metal Gear Solid 2)
The Pitch: "Two samurai - one a child soldier raised in the jungles of Liberia and the other his mentor and former President of the United States - are going to clash swords atop Federal Hall in downtown Manhattan. This is after a giant floating fortress called Arsenal Gear crashes into the city. Both of these men are also wearing cybernetic combat suits, one of which fires missiles out of its Doctor Octopus-style tentacles."
The Reality: What should have been cyberpunk samurai duel to the death ends up feeling like more of an awkward slap fight. Solidus' attack patterns are so rote and predictable that fighting him is like grinding through a dull Pokemon battle. Solidus used Dash Attack. Missed. Raiden used Sword Swipe. Hit. Repeat this for a good 10 minutes or so and the fight blessedly ends.
Yami (Tatsunoko vs. Capcom)
The Pitch: "Everyone loves the final boss fight against Yami at the end of Okami. You start the fight without any of your powers and have to knock them out of Yami one by one over the course of this multiform battle royale. It's an immense encounter that highlights all the skills and abilities you've collected, reflecting your long journey up to this point. Now we're going to transplant that same boss character onto a fighting game, where it'll have all the same grandeur and excitement."
The Reality: It didn't, not even a little bit. Yami may look the same and use some of the same attacks as it did in Okami, but in this new game it's simply a chore to fight. Consider Yami's size. Because it takes up about half the screen, you don't really fight against Yami so much as fight at it. Your assault barely fazes it as it just rolls from one attack to the next. But what's even worse is its hyper gauge-draining attack, which it uses constantly to ensure the fight lasts as long as possible by denying you your most powerful tools.
