This game is a game about hacking, that makes you genuinely feel like you are hacking, even though the mechanisms involved are almost certainly nothing like actual hacking.
Thanks to tight scoping, focussed design, and very cleverly constructed UI, you will work your way through this game in a state of near-constant tension. It is essentially a roguelike, so one false move and you’ll probably have to start over again. You learn many things along the way, but you still have to execute your plans well in order to succeed.
Introversion have gone on to make other similarly great games, like Darwinia, DEFCON, and the (currently in Early Access) Prison Architect. This is one of their earliest titles, and it still holds up very well.