Our story went through many iterations as we developed it. As both the aliens and astronauts made a binary decision at each "node" of our story, adding one layer of depth (another question) multiplied our number of outcomes by 4 each time. That, combined with the 4-minute performance limit, led us to decide to keep the story short. As we wanted the decisions to actually matter during the performance, there are many possible outcomes; the alien and astronauts can get along, both live, or everyone can die.
Originally, we had each decision pair (astronaut and alien) leading to a completely different scenario, but even at one choice per minute (so 4 decisions), we would end up with 4^4 (256) possible outcomes. Hence, we decided to loop the story back in on itself, collapsing similar scenarios together to make the storyline more manageable.
Our medium of creating the story also changed. We originally started with a flow chart (shown below), but quickly needed more context for each decision than a bubble or arrow could provide. We then used a Google Sheet and eventually a recursive JSON object to represent the storyline.