I'm a bit biased; I was in the process of making a game engine for a game a few months ago - turns out Factorio is pretty much identical to the idea I had. Fell in love with this game the second I started playing.

This game is virtually bug free, incredibly unrestricting and is a mega-base lover's dream. If you liked FortressCraft and can get past the fact this is a 2D game, you'll love Factorio even more (though I still recommend FortressCraft).

Something else really worth noting is that the developers actually give a ♥♥♥♥ about their game. They've posted several blog posts revealing their philosophies behind their decisions, even acknowledging the 'feel' of the game and problems they've noticed - most recently, the fact the game stagnates at a certain point due to the tediousness of larger furnace rigs. They've identified it and are coming up with ways to fix it. This is dedication and is proof that my money was incredibly well invested.

Oh, and there is a full mod system and multiplayer.

This is basically the holy grail for logistics gamers.