What if Scott never met Jimmy in that cave? What if Joel and Tango hadn't parted ways after making shields and taming dogs together? What if Ren didn't catch Martyn stealing from him? What if it was just a prank and Grian didn't owe Scar his life?
If you've ever wondered these questions, well good news baby, you've come to the right place to get some incredibly vague answers. I'm calling it 3rd Life: The Alternate Route (shortened to #3l:tarau in the tags) where I try to figure out how these small changes would affect the direction of the first life series and YOU are required to ask me questions and brainstorm with me to make me write and draw this, because otherwise it's just gonna get all dusty in a random corner of my brain. More below the cut.
The biggest changes in the early game are the teams (if Scott and Jimmy don't meet theres no Flower Husbands, if Martyn doesn't become Ren's advertiser there's no Dogwarts etc.). In this au, there are four main groups and two loners.
First of all we've got Jimmy and Ren who meet in a cave and decide they should stick together, at least for now. They continue mining, go to a few different caves to find diamonds and decide to set up a business together for people to come get enchanted, with both of them reaping the rewards. The name of this business? Why, it's-(engagement farming, please let me yap about this)!
Next is Joel and Tango, who work together to get shields and dogs and decide to stick together because there's safety in numbers (and Tango doesn't want to build a house, he's a redstoner, not a builder). They set up on the yet-to-be-named Dead Bush Hill and become dog breeders, because there's safety in numbers (their number will increse quickly).
Martyn, Grian and Big B are the first three to get diamonds, and Martyn decides to use them to make each of them a diamond sword. They go their seperate ways but eventually meet back up and decide to tear down the dark oak forest in the top corner of the map to 1) make a monopoly and 2) have cool wood to make their base out of.
Cleo, Bdubs and Impulse make a base and go mining, finding Scar underground and sharing diamonds between themselves. They make a base by the water and eventually make their way to the village with Etho to become the Village People before abandoning that idea and making a castle (with all aforementioned players).
The two loners are Skizz (like canon) and Scott, who still makes it to the flower valley and decides to set up there, becoming biome neighbours with Joel and Tango.
This is a response to a comment by @flyingducksoup because it didn't quite fit in a comment. I hope these answer all your questions :)
1) Jimmy and Ren are two idiots whose first loyalties are to each other. Jimmy mostly just tagged along with Ren after they found each other and as such if more of a follower. Ren is still dramatic and a bit inappropriate which Jimmy will sometimes bounce off of and other times scream "PG!", but I think they'd get along well.
Tango and Joel are all about being the last players left. They're all in when one of them suggests doing something that could worsen everybody else's lives and get a bit silly about it (Joel's plan to make a lilypad monopoly, Tango's Dare to Flare game (Joel thinks they should rig it)). They also really want to burn stuff down together, which they get the chance to later.
Grian, Martyn and Big B do their own thing a lot of the time, but I like to think they'd have a goal to complete each session that they'd scheme in their dark oak tower. Initially, Grian would have wanted to be on good terms with everyone, but Grian and Martyn are known pranksters (see: 3rd Life session 1) and Big B knows how to keep a bit running (see: Secret Life) so they'd do things to annoy the other teams that would eventually escalate into something deadly. Just like in canon, but a bit later on.
For the big group (Cleo, Bdubs, Impulse, Scar and Etho), Impulse, Scar and Etho are all floaters. Impulse is trying to make the others his "secret girlfriends" and is friendly with every group like in canon. Scar has a separate, smaller base in the desert to "protect" it but still pops in quite often to see how everybody's doing. Etho goes between staying in the village and staying in the castle until eventually staying full-time in the castle. Cleo and Bdubs are basically a married couple, like in canon, and Cleo is the main voice of reason in the whole group. One thing is that Scar still burned Etho's dark oak tree in session one so there is some tension between them as Scar teases them about it and burning down the other dark oak forest when the group learna about it. Cleo has to get between them to act as the mediator, Impulse tries to talk Etho down when he's around and Bdubs likes to rile them up when Cleo isn't around to cause some drama. They have fun.
Skizz's strongest alliance is with Ren's faction like canon and he acts as a close confidant to both Ren and Jimmy.
Scott's strongest alliance, at least near the beginning, is with Joel and Tango. They don't get along swimmingly, but because of Scott showing them the dark oak forest and them living in the same biome, they don't antagonise each other and work together when they need to.
2) At the start, yes. It does snowball later on like it did in canon and there are a few rivalries, even within teams (see: Scar and Etho).
3) I wouldn't think so. Scar might, but people wouldn't be as incentivised to get a good reputation with him because he loses his lives a bit later on, so it would just another thing that doesn't catch on.
4) Pretty much all monopolies are doomed to fail in the life series. When Ren digs down into the cave to meet Jimmy, he does it from the other dark oak forest biome, and Scott still lives right next to it. Scar is still delusional about making sand a scarce resource and failing to convince his teammates to dig it with him. Joel decides to get every lilypad, then every dead bush when that fails, but neither work. In that aspect, not much has changed.
5) It's no SoliBeanSmajorWood: The Fantástico (because that was probably Martyn's idea and he's one of the guys trying to make the monopoly) but once Scott gets told by Joel and Tango they go to the other dark oak forest and Scott starts handing out saplings, including to Martyn who tries to get him in on it and asking where Scott got them, but Scott refuses to say (he's told everybody else who's asked). Every base includes some amount of dark oak to spite the failed monopoly.
6) In terms of first death, I'd say session 2 Bdubs for the same reason in canon (hit off a pillar by a phantom) because no one dies in session 1 as far as I've made out. The order might change but it's the first death that would stay the same, because Bdubs still wants to build a castle without a safety net. If you're talking about first elimination, that is something I have planned out and it is a very different context to canon, but you'll just have to wait and see for that ;)
7) What I've mentioned is basically all the starting groups, and it doesn't shift around too much. The earliest alliance would probably be Joel and Tango, considering they meet up pretty soon after the start of the game. The early game isn't as different because it takes time for the small differences to fully develop, and the session one stuff is at the start.
I hope those were good enough answers and thank you so much for asking them, it was really fun to respond to.