Factorio - cool game about automating & production lines

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If you've enjoyed mods for Minecraft that add machinery, or trying to perfectly set up stockpiles and workshops in Dwarf Fortress, this game might be your new crack.

It's currently in alpha, planning to release in summer 2015 but already has a simple campaign that introduces the concepts, and I've spent the last two days in free play mode where the goal is to set up a hyper-expensive rocket defense to defend any would-be colonists (game ends without any colonists actually landing mind), so even there you have a goal rather than pure sandboxery. Highly recommend.

I forgot to say, there's a free demo available with the first three campaign levels:
https://www.factorio.com/demo