- Spoiler: show
Finished this the other day. Played a few hours when I bought it Feb last year, before Sekiro took over, and decided to wrap it up recently. I've enjoyed sinking hours into its sunny and green game world. No fortified trucks, motorways or helicopter chases since it's set in 10,000BCE, and when you're not in combat it often feels really calm and lovely.
The spear is the MVP of the combat encounters, but I also had a lot of fun stealthing up forts, dropping bee bombs on fools with my owl, picking off lookouts with the bow and arrow then going in to finish the job with my pet sabertooth. Also unlike in the Flintstones, this sabertooth never locked me out of the house. I think we just had a better relationship.
Also, the base building is simple but really satisfying as you build and upgrade the huts for the NPC friends you've found. It's nice coming back to Takkar's village to find a little community with children running around.
Overall really good versions of those outpost-clearing and base building loops and a beaut of a world. Fair warning though, there are a couple of pretty drab wave-based boss fights, one in particular is an absolute stinker and probably the worst and most frustrating encounter I've seen in a Ubisoft game. It's a shame a title about roaming, crafting, surviving, hunting and taming beasts couldn't have a climactic sequence that related to those things.
I mopped up the side quests and saw the credits, but I can see myself going back to chill with my caveman buddies when I fancy spending a bit of time in Oros again.
It looks like there is plenty of reason to keep going back with unlocks. 
