Probably THE best full-hacking experience available in video game form.
Encompasses what you would expect from Hollywood-style hacking, simple and accessible enough where playing it isn't a chore, but still challenging and interesting enough to have you hooked for countless hours, and you're sure to play the game from the beginning many times.
The main story is actually quite engrossing too, where you either help a corporation destroy the Internet with a virus, or help a rival company develop an anti-virus and take down the antagonists.
The game is entirely text and 2D graphics based, so even though it's from 2008, it doesn't suffer for it, it looks just as fine as it did the day it was released.
No other game, past or present, has captured hacking in video game form better than this game. If you've admired hacking in Hollywood movies and want a tense gaming experience mimicking that, chances are you've already played and loved this game. But if by chance you haven't, pick it up immediately.