Sandustry is a pretty neat "pixel physics" game (Factorio x Noita) but still in a rough Early Access.
Sandustry is dogshit and it's unlikely to improve because it's pretty evident the dev isn't really a gameplay guy. I don't really understand why it made a splash, I guess the publisher is doing their job.
The completely unknown
Atomcraft is the true falling sand game to satisfy Factorio player tisms. Your goal is to fix a rocket by collecting (nearly) the entire periodic table. You do this by eventually engineering dozens of little (or big) per-pixel chemical reactors for distilling, smelting, and reacting/reducing/whatever shit you dig up into what you want (or supplying sustainable fuels/reactants for your machines), as well as spending the products to unlock gear for your mining trips and tech to build more advanced little factories.
You spend most of your time in Sandustry suffering because it tries to prop up the poorly-thought-out factory-flavoured stuff by crippling the fuck out of the player so the molasses-ass conveyor belts and shit (which I guess have to be slow as shit because the "belting everything into a central factory" premise doesn't really work in a 2D game of this sort so they'd run empty immediately otherwise) actually seem worthwhile--only for that all to run empty and be ignored by the midgame anyway when you have more ingredients/cash than you need and are working on other shit... while your movement speed and tools remain gimped as fuck forever.
In Atomcraft you spend pretty much the whole time doing the actually fun part of planning out, troubleshooting and improving the little contraptions you've built.
Or just admiring your solutions as they run. Which is an aspect Sandustry also lacks, since most shit can be accomplished exactly one way and it gives it to you in a tooltip video, while any obvious interactions that seem like they should work simply don't if they aren't in the gifs.
NB: there's a comprehensive lookup system in-game so you don't need to be a chemistry nerd, except maybe for endgame decay products, which can be bypassed by just fucking nuking the planet's mantle or whatever and filling your pockets. I can't into chem shit but I had a blast and learned some things.