There is no AI companions, except the aforementioned Wolves (and another beast later), there is one Trader NPC (technically the bird is a NPC but he just gives you advice when you first start, then hes off).
There is no quests to do, no story to uncover, no deep lore...

... this all sounds bad right ? Well its not really, you get a whole relatively intelligently random world all to yourself, the only quest is set you at the start and you can do it as and when you see fit.
The world is your playbox, and the game says have fun.
A solo player can easily go through all the content, a bit more preparation may be needed as a solo but no MP gated stuff, its all yours... if you can take it.
The game does go through a linear path mostly, you move from biome to biome progressing up the power scale, but you still do go back to old biomes for resources.
Graphically the game looks like a old PS1 era game, but the environmental effects and lighting enhance the game world to something very pleasing to the eye.
Theres already a load of mods should you find you want more than this early access offering (which is a lot in itself).
If you can set yourself tasks and goals, and just enjoy the journey, the game is easy to recommend... and its cheap, and has more to come.