TLDR: definitely a grand pick for Factorio fans from an indie dev who appears to be the fan of the latter themself.
I like it about the community of music artists when they remix each other's pieces, which is both a compliment and a way to say, 'I would still change/add a few things'. One may say that modding and cloning are the equivalents of this activity in the world of indie game development, so, yes, I feel compelled to call Mindustry a Factorio remix. What actually got remixed and how?
Heavy accent on tower defense mechanics
If you ever felt like there was not enough battles in Factorio, this here offers a lot more defensive structures (walls, towers, auto-repair...) and drivable bots to choose from; more enemie varieties as well.
A specific innovation that both Mindustry and Factorio employ is feeding towers with ammunition. If this idea is not new (like everything under the sun), it is certainly underused or misused in the modern TD titles.
Towers are useless without ammo. While the low-tier early game towers consume raw resources for ammo (e.g., Copper), the high-tier towers consume crafted materials (e.g., Carbon, crafted from Coal) or rare resources (Oil, Titanium). Resources and Materials are also used in construction, so balancing the defense capabilities with the speed of expansion is one of the tricks.
Certain advanced towers can be further upgraded with additional supply of liquids that serve as either a coolant (Water) or lubricant (Oil).
It goes without saying that space is limited and stuffing all the supply lines in neat structures is a puzzle minigame by itself.
A distinct level up above Factorio is Mindustry's factories that produce drivable war machines non-stop (supplied with enough resources, of course). A player can either control one of them (which turns the game into an action shooter) or leave factories working, and the bots will crawl towards enemy positions according to pre-set logics.
Traditional tower defense waves
Surviving against increasingly strong enemies either until they win over or the level objectives are reached is essential to Mindustry's gameplay. The said objective is usually "collect this much of that resource", or "destroy enemie base".
A player-controlled airborne vehicle hovers above the battlefield: it is the first line of defense should no other means of protection be online by the time (or if the player enjoys kiting and harassing the enemies like this). Every time this default vehicle is destroyed it will respawn on the home base shortly. More powerful player-controlled vehicles are available later in the game, as soon as a respective factory is built.
Resource management is so much simpler
Concerning the math behind supply chains, well, it is not deliberately chaotic.
The train of thought I usually had during my Factorio runs was like, "A yellow conveyor transports 15 chunks of materials per second, but it is two-lane, which means 7,5/s on each lane... and this factory eats up 2/s... but the Inserter is the bottleneck anyway because its turn rate is 357 degrees/s... I therefore need a Stack research or a Fast Inserter here...", and so on and so forth.
In Mindustry, on the other hand, one coal mine comfortably feeds two Graphite factories, no more and no less, for instance (if I remember it correctly). In any case, you only deal with integers or simple fractions (1/2, 1/3...) to answer the usual automation questions: how many mines, how many conveyors, how many factories, etc. And no dozens of mind-blowing 4-component crafting recipes: Mindustry's craftables are usually made from up to two input components.
Storage is revamped completely
First off, resources are infinite but Extractors can only output that much of them, according to their mining rate and the number of patches they sit on. Considering how quickly Towers and Factories burn through them, it is hard to stash some. For me, it has always been easier to build a balanced production line. The game dynamics itself does not encourage resource buffering.
Tech research is separated from the action
Take all the time in the world to stare at the tech tree between levels; the levels themselves are fast-paced and give no respite to pondering players.
Who doesn't love huge tech trees, eh? - Source.
A late-game Launchpad building is used to collect and "send" resources into space, later to be spent on upgrades that correspond to individual playstyles.
It is unreasonable to farm resources ad infinitum, holding off the victory for as long as possible, because every next level gives access to larger resources patches and ramps up resource rarity.
Inserters? Off with you.
In Factorio, Inserters are intermediaries between all storage structures and consumer buildings. Direct supply from a Mine to a Factory is possible but rarely used: it is inconvenient. Because there are dozens of Inserters in perpetual movement, a player's screen would look like an ant colony - and there is a peculiar charm in that, no doubt. Building orientation matters to determine where a particular extracted resource will be put (e.g., in case of Mines) and where the input liquids will go.
In Mindustry, all buildings can accept and deliver resources to and from any side. And not just any side, any 1-tile wide border, be it a conveyor, dispenser, or another producing building. They just pick any appropriate spot, which allows for more dense and compact builds. As you notice, the buildings are symmetrical in two axes: it implies that orientation does not matter.
Closing statements ♥
I first tried out Mindustry on my phone, and, god, it was a delight. A game like this requires precision in different actions, so the way all the interface controls were handled left me with a pleasant afterfeeling of admiration. Hell, the author, Anuke, is my little personal hero for nailing it with their game!
It is so simplistic in terms of graphics that it's hard to imagine a device that would not smoothly run it, and it matters for low-end laptops and phones a lot.
Mindustry demo still lies on itch.io somewhere, so I don't see why not try it out. Free on Google Play, as well. The Steam version was last updated this October, lots of juicy features on the plate.
Images from Steam or itch.io unless stated otherwise.