A fun and challenging game that leaves you wanting more.
Presentation: 9/10
The source engine looks great with Portal. The game runs evenly and smoothly. Death sequences could be changed a little as the reload time is too slow and not automatic.
Gameplay: 9/10
The idea of creating portals to reach the end sounds somewhat simple and possibly boring. But it is very fun to play. The story is short, too short and there isn't really a plot. You solve these 'tests' before you try to murder Glados. The plot isn't that interesting but the puzzles, oh dear god, they're sooo good. You could never get bored of them but unfortunately there are only 19. After that you go through a long and tedious section of platforming. It's not hard, it's not easy and goes for too long.
Overall Portal shouldn't be a full priced game but it is an excellent inclusion as part of 'The Orange Box'.