Four years ago, PC gamers were delighted by a quirky game called "Portal." The object was to solve puzzles by creating doorways through walls, ceilings and floors while avoiding a female robot bent on killing you.

A strong sequel has arrived at last with "Portal 2."

You solve puzzles using a portal gun. As you can imagine, you shoot the gun to open two portals: Walk through one and come out the other. While that doesn't sound complex, the puzzles are.

Then you encounter some friendly robots to team up with, while the omnipotent artificial intelligence running the dilapidated Aperture Science Laboratory frowns on your survival.

The game's strongest appeal has to be in its witty writing. Often when taking a momentary break to scan the room and search for your next move, your robot pal will bust into hilarious dialogue that is sometimes helpful, other times just for giggles.

When even the villainous AI makes clever quips while trying to send you to your grave, you know it's a good game.

Once you complete the single-player campaign, there is co-op play with new puzzles and more challenges. I might even be able to convert my "Mario games only, please" wife into enjoying this one -- no small feat.

A quarter into 2011, "Portal 2" is one of the top five releases of the year and a game everyone can enjoy.