I think the most important thing is to make sure they have an ample library of software for the machine .. in my case, we have almost everything that was ever developed for the Oric/Atmos, and recently got it set up so that its very, very easy for the kids to play with ..
My kids complained about 'not having enough dots on the display' and "why are there no good games on it - like Super Mario", but once I showed them a few of the classics (Manic Miner, Jet Set Willy), they got right into it.
Most important of all, however: play with the machine with your kids, too. This is a great way to get them interested - you do the typing, they do the reading. ;)
Minecraft, at least on Raspberry Pi, has a full API. It's likely a bit complex to get going with, but you might find you can build a layer your kids would find "useful".
I've been thinking about that, especially as my son keeps trying to do things that the game doesn't support out of the box.
He set up an "honor system" store where people were expected to asynchronously trade (by dropping) some commodity for some other commodity and got upset at people "stealing".
Either this generation of kids will be the best citizens the world has ever seen, or the worst.
Than put more programmable constructs into Minecraft-like games, obviously. And no, Redstone doesn't count - stuff that celebrates ease of coding, not difficulty.
