I would add that calling it hard core Minecraft might set the wrong expectation. It's derived from Minecraft (I think it originally started as a Minecraft mod with a different name before spinning off) but since then it's gone in a completely different direction to Minecraft. If you go into Vintage Story expecting it to be like Minecraft you're probably going to have a bad time because your Minecraft knowledge doesn't really transfer over. Minecraft is a lot more adventure focused while Vintage Story has gone the other route, it's taken survival as the central focus and the adventure is largely built around survival.

And it does survival very well because it actually turns it into a motivation to go and explore. If you just sit around you are going to die. If you don't set up a farm and cellar and collect food for the winter, you are going to die in the winter. If you don't find different types of crops your farm will run out of whatever nutrient you're using and you have to start refreshing the soil. If you don't find warm clothes you're going to freeze in the winter. Your survival also depends on the variety of food, if you eat only one type of food you'll have less health (more variety in food means more overall health). You get so many external motivators to go out and explore simply because if you don't do it you won't survive. And in that sense I actually find exploration in Vintage Story a lot more rewarding that in Minecraft.

I would also add that Vintage Story has a modding scene and some of the mods IMO are kind of a must-have QoL updates. I haven't tried the most recent update so I don't know if some of those things have been improved or not. The mods I recommend are Auto Map Markers (because you want to mark down whatever resource you find because you're probably going to need it. This mod automates that), better prospecting (I would recommend first trying out vanilla prospecting before using this mod. This mod makes prospecting less annoying) and Carry on (at the start you don't have a lot of storage space so being able to pick up chests and move them around is very useful).