SPICE is a general-purpose, open-source analog electronic circuit simulator. It stands for Simulation Program with Integrated Circuit Emphasis. ngspice is a successor, and is easily installable on Linux. It’s the simulator I’ve used to explore the Skywater 130 PDK.
Here’s an example spice simulation file that I used to simulate the inverter I drew.
And here’s a nice demo of me showing how a flip-flop works by simulating a Sky130 D type flip flop with SPICE.
It would've taken me months, if not years, to make the progress I made in a couple of days. The tutorials are so helpful and the focus on practicality blends so well with the way I learn. I love it!