Fun: 5/5 This game is very fun. Even though I've played Valve's Portal, this game stands on its own as an entertaining game. The challenges increase quite quickly and the maps are well made.
Difficulty: 1/5 The game is very easy to learn. The controls are minimal, explained clearly, and the concept of portals is grasped quickly.
Visuals: 4/5 The visuals are good, but not stunning. I rate them high in that the visuals don't detract from the point of the game- to navigate the given map.
Engaing: 4/5 The game drew me in from the beginning. The difficulty increases at a rate such that progress is possible, but that games don't become too difficult.
Recommendation: 4/5 This game is a nice introduction to the concept of portals and is an excellent time waster.