Obviously spoilers for the entire game.
On my first play through the first thing that went wrong was Tammy dying, After that I did not at all focused on agriculture, I also didn't go out on expeditions so I didn't gather any food. So when the famine hit Sol's mother died. After a while Sol's father died from the infection/spores. The colonies defenses where also pretty bad :/ The colony did manage to survive in the end but it wasn't that great overall.
On my second play through I managed to save Tammy find a cure for Sol's father, but did not manage to save Sol's mother. I tried to date Tangent this play through which was a mistake as it lead to the eradication of Vertumna IV wildlife. The play through's after that where definitely better spoiler