A time paradox or temporal paradox is a paradoxical situation in which changes to past events due to time travel alter the cause-and-effect relationship of the present and future. Since the prequel games in the Metal Gear series allow the player to travel back to and enact past events in the saga, certain actions can be performed that would conflict with the continuity of the series' established timeline, for example, the death of a significant character. The Time Paradox screen, featured in Metal Gear Solid 3: Snake Eater and Metal Gear Solid V: Ground Zeroes, either follows or takes the place of the traditional Game Over screen, respectively.
Metal Gear Solid 3: Snake EaterEdit
If Naked Snake is killed, the game comes up with the traditional Game Over page displaying "Snake Is Dead." After a little while (or quickly if the player selects Exit instead of Continue) "Snake Is Dead" changes to "Time Paradox." This is because Naked Snake is revealed to be Big Boss at the end of the game, the genetic father of Solid Snake, Liquid Snake and Solidus Snake, and if he were to die, all subsequent events could not take place. If the Game Over screen is triggered via the use of a fake death pill, the point at which the "Time Paradox" message is completed marks the point at which the fake death becomes real. In this scenario, the player can access the gadgets menu and select the revival pill to quickly reverse this process so that Snake can stay alive.
A grenade can be thrown through the window of the room Sokolov is being held in, bringing up the Game Over page displaying "Mission Failed." His death compromises the Virtuous Mission, as he would not be able to complete the Shagohod. Sokolov also plays an important role during the San Hieronymo Incident.
Ocelot can be killed if Snake shoots, stabs, or throws a grenade at his unconscious body near the end of the Virtuous Mission or kills him while he is on the catwalk during the fight with Colonel Volgin, bringing up the Game Over screen and the message "Ocelot Is Dead." As with Snake, Ocelot causes a Time Paradox because of his involvement in future events (such as being the one responsible for the loss of Naked Snake's right eye). Ocelot is also one of the founding members of the Patriots and is the right hand man of Liquid Snake and then Solidus Snake. His death would also impede a future Old Snake from trying to kill Liquid Ocelot in 2014 because he is already "dead."
This is hinted at by the achievement/trophy in the HD version of Metal Gear Solid 3, titled "Problem Solved, Series Over", obtained by causing an "Ocelot is Dead" Time Paradox. After all, knowing Ocelot's actions in the future would make killing Ocelot in Metal Gear Solid 3 a logical step. But in doing so, would make the series stop at Metal Gear Solid 3, canonically the earliest point in the timeline.
If EVA is killed, a Time Paradox is created, bringing up the message "EVA Is Dead." She is essential for the completion of Operation Snake Eater, as she is the one who pilots the WIG out of Tselinoyarsk, as well as fighting the Shagohod and escaping Volgin's forces. EVA also plays an important role in later events, becoming a founding member of the Patriots and the surrogate mother to Solid Snake and Liquid Snake, and serves a part in Liquid Ocelot's Insurrection under the codename Big Mama.
Metal Gear Solid V: Ground ZeroesEdit
Should the player be killed during the "Ground Zeroes" mission, small text under the Militaires Sans Frontières logo reads "Time Paradox." It should be noted that this only happens during the main mission, due to the ambiguous canonicity of the side ops in Ground Zeroes.
- Metal Gear Solid 4 Database ("Time Paradox")