The Metal Gear series includes some of the best games of all time. It also includes some low-down dirty cheats built into the game allowing you to skip all kinds of drudgery. This is just one example of the many video games that reward you for cheating. Is it technically "cheating" if the game allows you to do it, though? That's the million dollar question. And since these are built-in shortcuts, you can choose to tell yourself the game creators snuck them in so only those as brilliant as yourself can exploit them.
These tricks, tips, and shortcuts will make some of your favorite games significantly easier. If you have a bit more gaming integrity, however, there are also a bunch of games that troll you for cheating. Be warned, there are major spoilers ahead for some of the most popular games of all time.
The 2016 Doom has one of the cheapest cheats you'll ever see. First, it requires the BFG, a gun so powerful it already feels unfair. Then, it requires you to be able to press the menu button. That's it.
The way it works is that immediately after you fire the BFG, quickly pull up the weapon wheel. This will effectively pause the game, yet your shot will continue onward. Not only can you not get hit, but whatever you're fighting will freeze in place and pretty much just wait to get blasted in the face. You can beat the Cyber Demon boss with a single shot because the plasma missile does continuous damage, and if you pull up the weapon wheel at the exact right moment, you can watch it drain the frozen monster's health from the safety of your pause screen.
Dead Space allows you to duplicate your items in Mission 3, effectively producing as many as you want, making the game infinitely easier. As IGN explains:
This is one of a few places you can exploit the game's placement of items. In mission 3, you are tasked to restart the Ishimura's engines. On your way to the engine room, there is a node locked door next to a set of malfunctioning, fast shutting doors.
Do not take items from the node locked room, but unlock the door and use the kinesis module to move the items (money, medikit, schematics, ammo) out of the secret room and leave them anywhere on the ground.
Use stasis to bypass the fast-closing doors and go to the end of the hallway to a save point outside the engine room. You do not need to save, just touch the save point. This gets you far enough from the node locked room to duplicate the items.
Travel back to the node locked room (past the fast closing doors) and some of the items in the secret room will be there, as well as the ones you used kinesis to move out last time.
This exploit stops working if you take any of the items (i.e., if you take the medikit, the medikit stops respawning) or when there are too many items on the screen (about 30 or so). If you need more stasis to get by the door, use the "Restore Stasis Energy" code seen on this page.
For some reason, Hideo Kojima really didn't want you to fight The End head-to-head. At least, one can reasonably conclude that considering the Metal Gear creator offered more ways to defeat the legendary sniper than just facing him in battle. There's an active way to defeat The End, and there's an extremely passive way to do so.
You can actually defeat The End before you even meet him. The End makes his first appearance outside the Ponizovje Warehouse as you sneak through the jungle nearby. He holds a brief conversation with The Fear, and during this time you can snipe him, taking him out so you never have to face him later.
There's another even less active (but brilliant) way to defeat the ancient soldier. This method requires you to actually enter into the boss battle against The End, but you don't need to finish it. You have two options to defeat him by doing virtually nothing at this point: you can either save your game and wait a week before returning to it, or you can save the game, exit it, set your Playstation's internal clock forward by a week, then return to the game. Either way, The End will die of old age while waiting for you. Snake will be forlorn with this approach, feeling The End deserved the glorious death of a warrior, but who cares? You just saved yourself a whole lot of bullets.
Power Bombs are extremely powerful weapons in Super Metroid. So much so, only a few exist throughout the game. As such, you have to wait a while before you come across your first one. That is, unless you use the shortcut. In the Norfair area, there's a tall shaft you'll come across you might entirely avoid, but if you can manage a series of wall jumps while avoiding some enemies and finally taking a well-timed shot at one block in the ceiling, you can make your way up into an advanced area. It'll take you through just a couple platform stages until you reach the first Power Bomb, normally unavailable until hours later in the game.