Planet Nomads may be the most appropriate as it does have a lot of building options. Even down to the level of small blocks. It also has a creative mode where you don't have to worry about the survival issues. But as you said, it is still early access and not free of problems. I think the story stuff is also far from complete, but that may be less of an issue if you're just looking for the building site of things.

As for the EA side. I've had it since the closed betas and they have done some impressive work on it. But as the past few months have shown, it has also been in a non-functional state on Linux (although not for everybody) for a while. The game could also do with a bit more optimisation.

As for a more traditional survival/crafting game, Stranded Deep is now on Linux too. Haven't played it myself (not yet anyway), but it always looked fun on streams.

Probably not easy/recommended for an 8 year old, not easy for anyone actually, but Don't Starve is a good one.

Not an ideal "Linux gaming" answer, but have you seen Roblox. This is literally a multi-player building/creative game made with kids in mind.

Can you clarify - Are you looking for Minecraft-style Survival-ish games, including single-player or only multi-player titles?

Wayward is a pixel-based survival game, with a free Web Version and a Linux Version on Steam.

Some other ideas: Terraria, Stardew Valley, Kingdom: New Lands, Kingdom: Classic, Colony Survival, Starbound.

Also there is Unturned free survival game on Steam. The art-style is basic, but the game is very detailed and might be too adult-oriented for your child.

Don't throw a stone at me, but there are a few for Windows.
Check out Green Hell, Raft or Stranded Deep (with Linux version). Whether they are worth the money is for you to decide.
My personal favorite is Stranded 2, but that is quite an old game, although there is a mod that makes the graphics better. It gave me many good memories and works well with Wine.

Quoting: g000hNot an ideal "Linux gaming" answer, but have you seen Roblox. This is literally a multi-player building/creative game made with kids in mind.

I am aware of Roblox, but I'm avoiding it for now - for one thing it seems that players can create anything and alot of the games seem to be basic FPS. I'm trying to avoid exposing him to games where the sole purpose is to kill/harm other people until he is a bit older and is able to more clearly distinguish between 'game behavior' and 'rl behavior'. Its not that I am against games with any pvp - heck minecraft has it, I just want it to be *a* viable solution for conflict resolution, not *the* solution.. if that makes sence :)

Also the fact that the very first ting I found when initialy researching the game was a very,very long article dealing with identifying, classifying and reporting online predators in game did not help in the slightest.

Quoting: g000hCan you clarify - Are you looking for Minecraft-style Survival-ish games, including single-player or only multi-player titles?

Minecraft craft/survival games with advanced building mechanics ala. redstone in minecraft - single or multiplayer doesn't really matter as long as multiplayer means you have an option for local/friends only games.

Quoting: tuxintuxedoCheck out Green Hell, Raft or Stranded Deep (with Linux version).

Raft is his the wish list because his favorite youtubers played it ( brave new world eh? ) - how ever the "slight" issue of water not rendering when played via steamplay has stayed my hand thus far

How about
Planet Centauri
Sky Break - you fight robots , so no violence to humans ?
Rising World
Maybe even Wurm Unlimited ?

Browsing Steam related games also came across this : Eco

Possibly Oxygen Not Included.

ONI is not a very hard game... but they recently added a mode setting for "Survival" and "No Sweat" modes when starting. Essentially Survival is the previous difficulty, so I my thinking is that no sweat is quite literal in its difficulty. And on the off chance it is too rough, people have started adding mods that really make the game easier.

The Don't Starve series and Terraria have got to be my top 2 recommendations. They are definately a must-play for all ages.
These games have endless replay-ability.