10 Video Game Side Quests That Impact The Main Story In A Major Way
2. LIMB Clinic Chip Upgrade - Deus Ex: Human Revolution
The rules of game design dictate that doing more things should yield greater rewards. The developers of Deus Ex: Human Revolution seem to follow a slightly different philosophy, however, as one of the game's side missions actually penalizes you for completing it instead of making your life easier.
At one point in the game, the main character, Adam Jensen, experiences odd visual glitches caused by a fault in his cybernetics system. This prompts a special side mission in which you visit a LIMB clinic and get a free chip upgrade that gets rid of the glitches.
The mission is entirely optional, and at first glance, it may seem completely irrelevant to the grander scheme of things. However, the difference between getting the chip and forgoing the procedure actually plays a pretty significant role later in the main storyline.
When the player confronts one of the Illuminati's leaders, Zhao, it turns out the free chip upgrade is a killswitch, which allows Illuminati members to forcibly turn off the cybernetics of anyone who gets it. If Jensen underwent the procedure, Zhao would turn off his augments, making the subsequent fight with her henchman significantly more difficult.
As if the world needed more reasons to hate hospitals.