I'll start off with saying this, I'm going to spoil some games here. The first Far Cry and both Uncharted games are top on my list. I guess by reading the title and this first couple of lines has spoiled something already but I can't help it.
Anyway, most games have a clear cut setting and purpose to the game. You're in this area or environment and you're going to be killing this certain enemy or whatever. Now some games can take a twist and throw you in a completely different direction and it's for the better. The first Doom comes to mind as a game that did this well. You're in a marine base fighting soldiers and some demons but by the end you're wading through Hell killing what I guess is suppose to be the devil. While Doom isn't know for it's story telling it was the first game that came to mind when I was thinking about games that did this change. But really there isn't a whole lot of games that do what I'm about to say. This thing I hate so much I usually refer to as "All of a sudden, monster."
First up Far Cry. I liked Far Cry I played it when it first came out and I thought it was a good FPS. Controls felt great and for the time it was an amazing looking game. You spend a big chunk of time going through the jungle killing soldiers not the most original thing but it was fun. Now it's been awhile sense playing this but I don't remember a big setup for what happens about halfway through or more towards the end of the game but it happens. All of a sudden you have to fight monsters, these mutated super soldiers things gone wrong. (It totaly hints at these monsters. I just loaded the game again and it shows them to you in the opening cinematic, I still hate that they're in the game) It completely ruined the game for me. I don't remeber if this was a twist I knew about going into the game but it still ruined the game for me. I killed one or two of these things and then closed the game and uninslalled it. I thought it was the dumbest thing I'd ever seen.
Then a few years later I played a little game called Uncharted (This all applies to Uncharted 2 as well), you're Nathan Drake in the jungle hunting treasure and smoking dudes along the way. Now I know this was never brought up before it happened but BAM! You're fighting zombie monster Nazis out of nowhere near the end of the game and it makes no damn sense. I was so close to the end of Uncharted when this crap happened I finished the game but in the end I thought it made the game just seem stupid. Uncharted 2 does the same gimmick but with these blue guys with bows and the same thing that makes these blue men powerful making the final boss just cheap and not fun to fight at all.
Another game from Crytek was Crysis and this game did the here are some monsters in the form of aliens but they were hinted at very early on and not just thrown at you with no rhyme or reason.
Now why does this bother me? For one if it doesn't match with the story it's just unneeded. In the case of the two Uncharted games it just wasn't needed, ever. They would of been better games without all that supernatural out of left field crap. But my one big time complaint with this happening is the game is never balanced for it. The whole way through these three games the challenge is fair and the guys can be taken down with your guns easily. The monsters appear and they are always way to powerful. In Far Cry after I killed a couple of the Trigen monsters I was completely out of ammo with none in site and more of those things in my way. Same thing in Uncharted 2 fighting the blue dudes. I know they're all suppose to be monsters and have poweres but half of an AK-47 magazine to somethings head should kill it, or how about you put the needed ammo around as you fight them. It's just ends up frustrating me, not at the challenge I like a good fair balanced challenge but when it's plainly broken it's just not right. What got me thinking about this stuff is I'm considering firing up the first Far Cry to try and finish it but having to deal with those blasted Trigens makes me not want to bother. I did finish both Uncharted games but in the end I thought the stories were crap even though I love the characters and how they interact with each other. I don't want to get into that right now so I'll end this here.