Pro-G writes: "Portal works so well it's unreal. The game subtlety introduces you to its mechanics with a learning curve that's just right. An important thing to mention about Portal is that despite it being a single-player puzzler, it works wonderfully well with a friend or two watching, helping you work your way through to the main game's climactic end."
"The simple ideas are often the best, and Portal, quite simply, is one of the best ideas for a game we've ever seen. It's fantastically realised, brilliantly executed, and had me wrapped around its computerised finger for two-and-a-half unforgettable hours. Don't let it become The Orange Box's forgotten son - this is gaming in its purest form."