Factorio is technically a strategy game, but certain aspects of the game feel more like a puzzle.
Each individual part of your factory (even small ones) can have an enormous impact on the rest of the factory, as can be seen quite easily with high-demand items such as Electronic Circuits or Advanced Circuits... or even just raw Iron Plates.
Automation is the key in this game, and you can automate almost everything (except for fishing... but oh well).
While there is some strategy involved, the puzzle-like nature of making a production line (placing the machines, laying conveyor belts...) is easily apparent.

Though it is not a puzzling as a dedicated puzzle game, it is still a fascinating brain game, and you will need to think as you play, as there is plenty of problem solving to be had here.

Then there is the dev team.
Some dev teams will take weeks, if not months to fix seemingly minor bugs.
Wube are not "some dev team". In the true spirit of the game they've created, they have automated many things for working on this game... from automatic crash reports, to an entirely automated testing environment,
One of the best parts, is Factorio's so-called "Experimental" branch, where updates are frequent as they add or change features and mechanics. But don't let the name fool you; Factorio's Experimental branch is far and away more stable than many AAA game's final release versions.
Of course, by its nature, Experimental does end up getting major bugs every now and again... but the speed at which game-breaking bugs get fixed is stunning. I'm reminded of the time where an update broke rail signals (a vital part of making a working train network), and there ended up being a rapid sequence of 3 updates as they worked on fixing them within a relatively short period of time.

The game is also extremely open to modding, having a fairly robust official modding API, and a dedicated Mod Portal (which even hooks into the game directly so you can download mods from in-game).
Even with the aforementioned rapid updates, mod-breaking updates are few and far between, and are usually given a fair amount of advance notice so modders can prepare for them.

On the dev team again, they are also extraordinarily honest. While the game has a very strict no-sales policy (even during steam's Summer Sale), the devs have commited to charging a fair price, without that nonsense .99¢ tacked on to it.

Factorio is also loads of fun to play with friends, and has a pretty well-designed multiplayer system. You can even load your single player saves in multiplayer, and vice-versa.
Finally, the community itself is incredible, with helpful individuals on all three major community areas: the official forums, their Discord server, and r/Factorio on Reddit.

All in all, Factorio is a welcome breath of fresh air in the rather stagnant environment that is today's games industry.
If you enjoy games that make you think about what you're doing, rather than just click things through muscle memory, you will absolutely love Factorio. My play time might be a good indication...
Although, fair warning... Factorio will absolutely grab you and hold on to you if you let it, and hours will fly by in what seems like minutes.

Factorio is technically a strategy game, but certain aspects of the game feel more like a puzzle. Each individual part of your factory (even small ones) can have an enormous impact on the rest of the factory, as can be seen quite easily with high-demand items such as Electronic Circuits or Advanced Circuits... or even just raw Iron Plates. Automation is the key in this game, and you can automate almost everything (except for fishing... but oh well). While there is some strategy involved, the puzzle-like nature of making a production line (placing the machines, laying conveyor belts...) is easily apparent. Though it is not a puzzling as a dedicated puzzle game, it is still a fascinating brain game, and you [i]will[/i] need to think as you play, as there is plenty of problem solving to be had here. Then there is the dev team. Some dev teams will take weeks, if not [i]months[/i] to fix seemingly minor bugs. Wube are not "some dev team". In the true spirit of the game they've created, they have automated many things for working on this game... from automatic crash reports, to [i]an entirely automated testing environment[/i], One of the best parts, is Factorio's so-called "Experimental" branch, where updates are frequent as they add or change features and mechanics. But don't let the name fool you; Factorio's Experimental branch is far and away more stable than many AAA game's [i]final release versions[/i]. Of course, by its nature, Experimental does end up getting major bugs every now and again... but the speed at which game-breaking bugs get fixed is stunning. I'm reminded of the time where an update broke rail signals (a vital part of making a working train network), and there ended up being a rapid sequence of 3 updates as they worked on fixing them within a relatively short period of time. The game is also extremely open to modding, having a fairly robust official modding API, and a dedicated Mod Portal (which even hooks into the game directly so you can download mods from in-game). Even with the aforementioned rapid updates, mod-breaking updates are few and far between, and are usually given a fair amount of advance notice so modders can prepare for them. On the dev team again, they are also extraordinarily honest. While the game has a very strict no-sales policy (even during steam's Summer Sale), the devs have commited to charging a fair price, without that nonsense .99¢ tacked on to it. Factorio is also loads of fun to play with friends, and has a pretty well-designed multiplayer system. You can even load your single player saves in multiplayer, and vice-versa. Finally, the community itself is incredible, with helpful individuals on all three major community areas: the official forums, their Discord server, and r/Factorio on Reddit. All in all, Factorio is a welcome breath of fresh air in the rather stagnant environment that is today's games industry. If you enjoy games that make you think about what you're doing, rather than just click things through muscle memory, you will absolutely love Factorio. My play time might be a good indication... Although, fair warning... Factorio will absolutely grab you and hold on to you if you let it, and hours will fly by in what seems like minutes.