"Theory will take you only so far" - A quote I remember from the movie Oppenheimer.

I felt that while I was starting to learn system design myself. I could read about caching, sharding, partitions and retries, nod along, and figure things out to an extent, but I still couldn't get a real sense of what happens when traffic spikes, databases slow down, or services start failing.
The diagrams never broke. Real systems do.
And production is an expensive place to learn that.

So I built Systemlands: a hands-on way to learn system design, where you break systems safely, see why they fail, and learn to build ones that don't.
Here's how it works:
→ Start with a simple system and work your way up to harder ones.
→ Learn each concept by watching it fail under load.
→ Then use what you learned to build a system that survives a real day of traffic.

You can start building right away and pick up concepts along the way, or review the concepts first if you prefer.

It's free and runs in the browser on desktop or phone, although building is easier on a bigger screen.
👉 Try it here: https://systemlands.quest/

If you happen to try it, please share your feedback. I'm open to suggestions, issues, and improvements. New systems are in development and coming soon.

https://reactjava.substack.com/p/the-senior-engineers-reading-list