Things I liked:

The whole presentation really got me into a hacker mindset, with the screen aftereffect (especially the fail animation), and particularly the key stroke sfx. I found the difficulty to be just right, hard without feeling impossible or completely overwhelming. I liked the design on a lot of the later levels, especially 5 and 7. You communicated all the commands diegetically, which makes it feel much less like a tutorial and much more like part of the experience.

Potential areas for improvement:

Some of the earlier levels felt a little redundant; it felt very clear that you can use commands before boot from the get-go. Level 6 felt too easy in comparison to the levels around it, mainly because I think there were an unnecessarily large amount of doors. It felt simple, but you seem to be working on changing that for the better, although you should probably keep in mind the tightness of the timing while typing multiple different commands-- it's already pretty hard. Also, the idea of a "crazy" virus feels very un-fun, particularly in comparison to the other ideas you mentioned, which seem like brilliant mechanics with lots of cool possibilities.

Overall:

You've committed to improving a game that already feels great, which I'm very happy to see. Given what you already have and the ideas you have proposed, I believe that you are fully capable of making this game even better than it already is. Good luck, and I'm excited to see what happens!