“We both said a lot of things that you are going to regret. But I think we should put our differences behind us. For science?You monster,” the villainous GLaDOS said in “Portal 2.”The first “Portal” turned a lot of heads when it debuted as part of the “Orange Box” back in 2007. The totally original gameplay and hilarious script made the original a hit.

However, gamers complained that the whole game could be beaten in about three hours, making it feel more like an experiment than a full game. Well, Valve is back for round two with a full-length experience that manages to capture the quirky magic of the original and make it worth the full price tag.

The silent hero of the first “Portal” is rudely awakened and forced into a whole new set of challenges inside the testing facilities of Aperture Science. You’ll be guided along your quest by a very British artificial intelligence (AI) named Wheatley, and have to survive the deathtraps and passive-aggressive insults of the newly revived GLaDOS, an artificial intelligence who has not forgiven you for “killing” her in the prequel. The story is downright hilarious, featuring the best comedy writing to grace a video game to date.

“Portal 2” is a first-person puzzle platformer that is essentially a long sequence of puzzles daisy-chained together in a massive testing facility. You’ll move from one room to the next, solving puzzles with the help of your trusty portal gun. You can create two portals at a time on the walls, floors and ceilings of the facility. Like the first game, the puzzles gradually become more and more mind-bending until you’re pulling off crazy stunts using infinite loops and principles of gravity and momentum.

There are some fun new additions to the gameplay in the form of Repulsion and Propulsion gels, which can either bounce the player away like a ping pong ball or increase their forward momentum. While in theory the process of solving a puzzle, moving to the next room and doing it all over again sounds monotonous, the sheer brilliance of the challenges will titillate your mind, making you crank your noggin on all four cylinders before reaching the solution.

The game’s funny dialogue and lovable characters will also motivate you to keep going. The main campaign is about 6 hours long, which is still shorter than most games these days. However, “Portal 2” features an entirely separate two-player cooperative campaign where each player controls a robot tasked with finding a vault full of human test subjects for GLaDOS to experiment. The puzzles in two-player mode are much more complex than in the single player campaign, requiring full cooperation to succeed. You can tackle this mode online or offline, though if you choose to play online you’ll definitely want a headset to communicate with your partner. Good luck using emoticons to tell XoXoAngelWarrior77 that he needs to place a portal directly under the pipe on the left instead of directly above the furnace.

Even with the co-op mode, “Portal 2” is a tad shorter than most gamers will prefer. You can unlock developer commentary after your first playthrough, which will fascinate some, but may not be enough incentive to warrant a replay for those not interested in the finer points of game design. Also, while the humor and setting will draw in gamers not usually interested in puzzle games, it’s still not going to be for everyone. I recommend a rental before you buy.

The game’s graphics are sufficient, squeezing the last drops out of the somewhat dated “Half-Life 2” engine. The environments are mostly austere testing rooms, and the music is equally restrained. Music will underscore key moments, but for the most part you’ll be listening to the fantastic voice work, which brings the game’s lovably villainous characters to life.

With that said, if you loved the first “Portal,” truly creative puzzles and witty writing, “Portal 2” sets the new watermark and hides it in a labyrinth of wicked brain-teasers and dastardly deathtraps. It will be a while before anyone solves the puzzle of how to top this game.