Guide Dang It/Wide Open Sandbox

Want that 100%? You need a guide.

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• Just Cause 2, which has thousands of items, hundreds of locations, a thousand square kilometers, tons of quests, and far too many collectibles/destructibles that AREN'T documented in any way (identified as "something to do" in a settlement, etc.). It's almost impossible (if not flat out impossible) to 100%-complete this game without any sort of guide or 3rd party mod tool for the PC version.
• Some of the various collectibles spread throughout the Grand Theft Auto games are so tucked away and well-hidden that locating them all by oneself seems like a near-impossible task. One Egregious example appears in San Andreas, which has a Sidequest in which you must take pictures of photograph icons spread throughout the game. While several of these are damned well-hidden, the most ridiculous one is located on the roof of a random, innocuous building. You can only see the photograph icon by flying an airplane on the roof itself, and not from on the ground or from any nearby buildings, although a player in the know can take the picture itself from the ground.
  • To be fair, one of the flying missions does pass over those buildings. And it's quite likely a mission you'll have to repeat a few times. Damn plane...
  • Here's the secret: the snapshot locations glow with a strong pink light at night. You can see it from an in-game kilometer away. If you ever stop and wonder where that shine comes from (it has no apparent source), you'll zoom in with whatever you have and see the icon. Problem solved.
• In The Godfather 2 there are several Made Men waiting for hire around the cities who start with two specialties compared to the one of most and better levels of weapons training. The problem is that the places they can be found are usually not obvious.
• L.A. Noire frequently gives the player several possible leads to follow up at various points. However, sometimes one lead will provide evidence that can trap a suspect in a lie in a later lead; if you follow the leads out of order, you may be unable to challenge a suspect's lies. The game never warns you, it falls entirely to the player to figure out in advance, which is sometimes nigh-impossible without psychic foresight or a strategy guide. Luckily, neither the game nor any individual case becomes Unwinnable by botching an interview.