No gilding of the lily today - here's an excerpt from "Apocalypse When?", the setting and lore information for Substitution v2.

The End of the World, Substitution Initiative, and Spacetime Ripples

There was no single event or actor that caused the apocalypse, but rather a cascade of things over the course of about 20 years that ended up killing nearly all of humanity and ended civilization as they knew it. Between natural disasters, diseases, war, and intentional destructive acts, the generally agreed upon year of the “End Of The World” was 2324, though different factions of humanity have slightly different numbers.

The Substitution Initiative was established in October of 2401, with the first Substitute being sent back on June 10th, 2402. The intent was to arrive in 1998, but the technology was untested, and the lack of available data made it difficult to land in the correct time. After the Substitute’s mind had already been uploaded, the team had to act on the fly, and a new year was chosen. The agent arrived on June 10th, 2002, 400 years in the past.

Due to ripples in spacetime created by Substitution, once a Substitute or message has been sent back in time, nothing can be sent before that specific point in time. This means that when a person arrives in the past, they are, for that moment, the most recent person to come from the future. The Substitute Initiative employs extremely talented individuals, known in the future as Monitors, to keep an eye on the ever changing timeline. The Monitors advise the Superintendent when sending back missions.

Eras of Play

The default setting of this game is 2022, a time we are all familiar with. The Substitution Initiative has been active for 20 years, and there have been thousands of Substitutes sent back before you and your team. There are plenty of active agents in 2022, meaning your players have many options for allies and rivals. The Initiative has been in place long enough that the future has been changed in small ways, meaning an agent who arrived five years ago may remember a slightly different future than you do.

There’s nothing keeping you as a play group in 2022, however. Any time from 2002 through 2304 are viable options for eras of play. Here is one example:

2002 - 2006: The Early Days

The Substitutes of this era are the pioneers of time travel, a barely-tested, barely understood technology even in 2402. While the first person sent back was a success, it very nearly failed, and there were at least 20 documented failures before 2006. With the rise of Facebook in ‘06, social media began dominating the world in a way Myspace had not quite managed, and sending back Substitutes became much easier.

All told, there were only six teams successfully sent to the years 2002 through 2006, and three more teams who lost two or more members in transit. Your team is one of these, completely on your own, with little or no access to the others. Substitutes are sent all over the world, so individual teams are rarely within a thousand miles of each other at this point.

Missions during this era are the least focused, as it was difficult to know how much one event could change the future. While many missions involve saving or killing people, or stopping some kind of terrible event, there are also many missions whose sole purpose is to test the so-called Butterfly Effect. Buy this stock, rob this store, befriend this person; these missions are often innocuous or seemingly unimportant, but used as data points by the future.