The game is all about automating a factory. It's basically a survival game with most of the survival and grindy bits ripped out and turned into better crafting mechanics. If you like games like Minecraft or OpenTTD, you'll probably like Factorio.

One of the impressive things they've managed to do is make the multiplayer scale quite nicely--how many other games can say they have 400 concurrent players on one map and still be playable?

Automating a factory, then redo it so the ratios are right, then again so it's more efficient, then add trains. There's also the circuit system for automating further and doing fancy things like this: https://www.youtube.com/watch?v=indN4kcshB0

It's also quite[0] addictive. You may find you burn a lot of hours.

Exceptional value for money if it's your sort of thing.

[0] The Cracktorio nickname is well deserved.

The website and the sibling comments already gave you an impression of what game it is in general. If that sounds okay, give the demo a try. I liked it, but wasn't convinced to spend money just yet because the demo is quite small. A friend sent me the Linux version (no DRM) and that convinced me soon enough. If you need the full version and solemnly swear you'll buy it if you like it (you will need to for updates anyway), let me know! (Contact info in profile.)