I've joined the party late.  For $5 on Steam you can play this accessible game with purest game play and ample amount of challenge, but all at a pace that you decide.

Game Mechanic

At the very basic level, your task is to assemble and paint complex shapes that are made from basic shapes at each quadrant, at each layer.  You start with basic tools to mine basic shapes and colors, cut, and paint them, while conveyor belts to connect all your tools.  As you level up you gain new tools, the next shape you need increases in complexity.

This is a brilliant design, since not all the tools are available immediately, first-time players will familiarize themselves with what they have as new concepts are introduced gradually.  The stacking rules are sometimes very obtuse, and so until one learns the rules it is not possible to make the shape and level up.  This gives short-term goals that can be managed by individuals.

Long-term, you want to produce shapes faster.  So this means planning routes and locations for your tools.  For one level, the way to level up required that I not only build the shapes, but to achieve certain delivery throughput.  So the game insists that you optimize your designs, which allow you to level up and upgrade your tools faster.  It even exposes a handy meter that tells you how fast things go under it.

Finally I recently unlocked the wires layer, which exposes tools to programmable logic that you can piece together.  This layer has the similar concepts as the main layer, except that it runs wires instead of conveyor belts and exist on a separate plane so the two layers work together to enable more interesting automation.

Large Scale

There seems to be no limits on how far away you can scroll, and while you don't want to make your shapes too far away from the delivery hub, this scale is truly awesome. Without being tied to physical objects, only possible in a game.

Copy and Paste

Once you settle on a design you like, you can replicate it anywhere else on the map by copying blocks and pasting wherever you like.  Any world building game should have this functionality.  Nobody wants to be doing something they have already mastered.

Map Marker

As you zoom out, you are presented with a map that you can annotate with markers and a helpful description.  This way you can find your way around the map without having to memorize the spatial relationships between parts of your system.

Shaper Viewer Web Page

There is a web page that renders the shape for you: https://viewer.shapez.io/

So very useful.  With its 8-character-per-layer code you can annotate map markers with shapes grapically, perfectly complements the map.

I also use it to figure out the signal I send for filters, one of the tools that is making the game much more enjoyable for me.

Overflow Storage and Buttons

It seems obvious to me now that you cannot have (fun) an automation system without them.  But I must admit that I struggled to figure out what they do and how they interact with each other.  The problem is that it wasn't clear to me initially what the signals from storage meant.  Before the storage I had built these looping tracks to buffer shapes, and having access to the storage tools was the reason why I deleted everything the first time.

No Restart

You lose all your levels and tools if you start a new map, so the game is asking you to delete and refine existing work.

I have mixed feelings about this, because deleting a lot of blocks is error-prone for me.  However I can see this helps you to carefully plan and commit to your designs, and manage them however you can on the map.

Speaking of deleting a lot of blocks, I have deleted everything from my map three times: 1) when I received storage tool, 2) when I realized that merger and splitter tools can achieve same mixing and stacking throughput as speed of conveyor belts, and 3) after unlocking all tools the goals are now achieving certain delivery speed, so I had to clean up conveyor belts around the hub.  Each time it is a lot of work, but don't be afraid to delete nearly everything.  Because after certain levels, the goal shape is random, and seems to me only 3 shapes for upgrades and the blueprint shape for cut and paste are repeats from previous levels.

Virtual and Logic Tools

This games includes a set of tools that emit signals or process them.  I use them to prototype the design because you can generate shapes as signals and use them in virtual tools that mimic the ones that do real work.  Often this simplifies each level because I'd understand how to build the shapes virtually, then it is a matter of generating the shapes that match the signals I used in my simulation.

There are logic, analysis, and unstack tools, as well as the delivery hub emitting signals for the level's goal shape, that make it clear it is possible to automate many aspects of the shape building.  However, they take up a lot of space in the wire plane and are very hard to track for me.  I feel it is because functions are groups of tools and they often don't fit in a single screen on the map, and moving them around isn't fun.  Often the tools in physical layer emit signals and interefere with things on wire layer, having to switch between them is tedious.

I wish these set of tools happen sooner in the game, it would have saved me a lot of time trying to figure out the stacking behaviors.  For me they made a lot of the concepts and tools easier to understand.

Open Source

This game's source is on GitHub!  This is of great interest to me, and I am glad that the author has decided to do this, allowing others to learn more.

Conclusion

Due of shelter-in-place and coronavirus, I am spending a lot of time playing games and this game is filled with interesting, high-impact decisions.  I am probably spending an unhealthy amount of time playing it, and have lost significant amount of sleep.  But this is such an engaging and fun game, at a great price, that I highly recommend.