This entertaining game aims to be a scientifically accurate evolution game, starting off as a single-celled organism and growing into more complex organelles, competing against other organisms in the environment.
I don't know why people mention spore. It only has some similarities with its first stage. Thrive is never gonna be "from puddle to space adventures"-type of game.
After watching open source game scene for decades, I'm quite sure Thrive will end up being a good game in "puddle" level, but it will never be more than that.
Spore made a huge impact, not only in mainstreaming the idea of an evolving game but in the ability to control characteristics and shape interactively and easily. Plus being able to share creations online was huge, even though so many of them ended up in certain shapes (humans being humans). Where I think Spore failed is in trying to rush through the first stages and get to the "civilization" parts. It would have better if it had a slower pace staying within the animal world. They also failed when they dumbed down and sanitizing the original game, which was much more violent (see the demo with Robin Williams)...but that's how nature is.
Thrive is very impressive, but it might be too realistic in its complexity and trying to include everything and that will keep it from getting popular. If I remember you can dial it back some, but it's still very technical compared to the simplicity that made Spore work. Maybe there can't be a good middle ground.
There's still a lot of people who simply yearn for a more complex spore type game. Spore's first evolution stage was supposed to be quite a bit more complex to what it ended up being too. You can still find some old presentation video of it around on YT but the quality suffered as one of the older YT videos and only has the low res one on offer.