Timeline Zero is the original timeline of history in which all of the world's events occur. It was deleted from existance when Eddie Smith & James Anderson activated the Time Map with a warp gate & headed back to 950 A.D., creating a new timeline, Timeline A. Smith ventured to the future, experimenting the Time Map & would result in making 3 more timelines in the process.
Events had the timeline not been erased?Edit
Given that in Timelines A, B & C, the world was a post-apocalyptic wasteland in the year of 2200, it is very likely that even if Timeline A hadn't been made, the world would've still turned out this fate. However, Timeline D interrupted the events that would result in the decimation of life by having Jack Anderson head for the Radiation Factory to stop Cyber Erol from opening the Radiation Silo. If Jack didn't show up (which he didn't in the first three alternate timelines), Erol would've opened the silo to mutate human life & then fuel an alitronium bomb that would have the power to erase all life completely. Both of his attempts to destroy life were unsuccessful, resulting in mutations in the last survivors of humanity in the wasteland of 2200.