Portal 2

Portal 2 is composed of brilliant explorative puzzles. With a gun-like machine called the Aperture Science Handheld Portal Device, the player can create blue and orange portals which connect two flat locations. If you go through the blue portal, you will come out of the orange portal (and vice versa). If you shoot the floor and then shoot a distant wall, you can then jump into the portal on the floor and come out of the portal on the distant wall.

What's more, momentum and velocity are maintained through portals, which makes them fantastic for teaching physics. If you fall a long distance through a portal, you can use that momentum to "fling" yourself horizontally across a great distance (see below).

Portal 2 also introduced several new game mechanics, including colorful "gels" with various properties, such as propulsion and repulsion (which cause interesting speeding and bouncing effects).

This game is fun even when you know the ending, but beware spoilers below!

Portal 2 takes place in the universe of the game Half-Life.

In the game, you are awoken several years after the events of Portal by a robot called Wheatley. The two of you attempt to escape from a series of test rooms, and in the process reawaken GLaDOS, the evil AI from the first Portal game. She separates you from Wheatley. After you make it through a number of obstacle courses, Wheatley rescues you from GLaDOS and you manage to store her consciousness in a potato battery, giving Wheatley control of the compound. Unfortunately, Wheatley betrays you and pushes both you and GLaDOS down an elevator shaft, forcing you to begin an uncomfortable alliance to reach the surface and stop Wheatley.

Portal 2 contains significant backstory about Aperture Science and the character GLaDOS. It is also much longer, and includes a two-player co-op in which two rather silly robots named Atlas and P-Body attempt to cross puzzle rooms by working together.

Representation Portal 2 is a first-person game, so you cannot easily see your own body, but occasionally you can catch glimpses through portals. When you do, you see that the main character is a woman. What's more, she's a minority woman. Portal is a wonderful step for feminist gamers because the gender of the protagonist does not affect her characterization in any way, nor is she covered in make-up and donning a sexy outfit. Her look is realistic, and it's extremely refreshing. The antagonist, GLaDOS, is also a woman.

You can save at almost any point of Portal 2 simply by pausing and selecting Save. If you die, you are automatically returned to the last significant accomplishment in your gameplay (pressing a button, passing through a door, etc.). The game's many levels provide nice breaking points.

If you're playing Portal 2 on the PS3 or Xbox, you can play the co-operative level with other players online. If you have a headset, you can speak while you play. This obviously opens the door to unregulated content. Co-op play becomes available only after the single-player game has been completed.

Portal 2 is an exploratory puzzle game (often with multiple solutions), it's a great idea to try playing a few levels with your kids and seeing what methods they choose to solve each room. Try solving a few together, and talking about the process they go through to solve each puzzle.

Here are a few questions you could ask to start a conversation:

• Do you believe that artificial intelligences have the capacity for emotion? Does GLaDOS have a personality?
• If a person volunteers to be experimented upon, does that count as consent? At what point does the experimenter go too far?
• Can you separate the humor from the drama? What about GLaDOS is funny, and what is scary?
• What are some other games that don't rely on violence?