The French videogame newspaper CanardPC published a short interview of Michal Kovarik along with its test of Factorio.
It's paper-only and in French, but here's a homemade translation for non-French speaking curious Factorio players.
(hope it's good enough, especially as it was probably translated from English to French by the journalist before...).
CPC: How did you get the idea to make a game like Factorio?
Michal Kovarik: It came to me with the Buildcraft mod for Minecraft. While playing it, I immediately understood that industrial automation could be a good gameplay support and better yet with the ideas I had. So I started to think about a concept, I did some schematics during my boring meetings at work and implemented it during nighttime and weekends. This is how the first prototype of Factorio was born. Most content was not planned initially, it was added progressively during the development process. We've played relentlessly with the prototype to find what we like most and what was missing to the game. And now it's public, many ideas are coming directly from players in the forums.
CPC: The graphical style changed a lot since your first alpha version one year ago. Are you now satisfied with Factorio's look?
MK: Finding a graphical style was very hard at first, because we had no idea what the game should look like. But after hours of discussions, tests, mistakes and efforts from Albert, our artist, we finally found what we liked. Of course, the graphics changed a lot, but we are now satisfied with the result.
CPC: Are you finalizing the game, or should we expect new major features in the new updates?
MK: We want to avoid making a too complex game, so the current content reflects everything that's going to be included in the final version. We hope to deliver it in summer 2015. We now have to work on multiplayer, to polish a ton of small things, to extend modding capabilities. And probably also rework combat and interactions with aliens in order to add more diversity. Depending on the community's interest, we could perfectly continue to enhance the game once it is released, like what was done on Minecraft.
Note to Michal Kovarik: the first sentence in the last answer was not very clear to me (in the French version); does it really mean that all planned features in the final version are already in the game?