Well it is a Prototype that the developers created on their spare time while they were still students at Uppsala University. A prototype is supposed to showcase basic functionality and the core concept of a game. It became surprisingly popular (with over 7 million downloads in half a year since release) so devs decided to make a full commercial game out of it instead of finding work and continuing to work on Raft just as a hobby on their spare time once they graduated.
RAFT HISTORY
Raft started as a student project at Uppsala University, Campus Gotland fall 2016. A group of three students spent around 15 weeks half-time to create a prototype for a survival game set on an endless ocean. Said prototype was released for free on Itch.io December 19th, 2016, right before christmas. While the group was home on christmas break, Raft was starting to get noticed by more and more youtubers and gained a lot of traction on Itch.io.
By the end of May the prototype had been downloaded over 7 million times and was covered by several major youtubers such as Jacksepticeye, Markiplier and FGTeeV. This type of response came as quite the shock to the developers. They quickly decided to keep developing Raft into something bigger and better. With their sights set on a Steam Early Access release in 2018 they met with Scrap Mechanic developers Axolot Games in search for an investor and publisher. With their common passion for survival games both parties felt this was a perfect match and soon after decided to work together. With the support of Axolot Games, the team founded the studio Redbeet Interactive, moved to Skövde and continued the development of Raft.