Some feedback:

- Nice idea, though after playing Turing complete, I would like to skip the beginning and move to stuff that makes GPUs different to CPUs. But it's understandable.

- I'm not smart enough to intuit NAND from transistors. I'm also not sure I will be alone in that. It's such a weird difficulty wall.

- Speaking of, the difficulty is all over the place. Though easy mode is appreciated.

- Even with a n key rollover keyboard, I couldn't complete the capacitor refresh level. It seems like it speeds up and certain capacitors already start empty.

- The routing for wires is no good atrocious. Any level with more than 8 components will end up impossible to read.

- It doesn't help that you can't color code or even path wires manually.

- Might be Firefox only, but I had a hard time selecting the connection points.

- Dragging the mouse along the edge should pan. Otherwise you have to drop the connection and zoom.

- I appreciate the added "show solution". But it's not really giving you a solution. It's just a better hint.

- An option to show all tests or at least more tests would get great.