To those for whom I recommend games . . .

You have to try Braid.

It looks like Super Mario Brothers redone as a shimmering, moving, impressionist painting. It plays a little like Portal, but really unlike anything you've played before. The game explores the concept of time, how we perceive it, how it effects us. In each world, time operates in a different way, and there are maddening ingenious puzzles built out of the implications. Each puzzle teaches you something new about the logic internal to the world, and will make you think in a way you've never thought before. Once you've figured out a puzzle it doesn't require much more physical dexterity to complete than getting through the first few levels of Mario, but some puzzles may take hours of thought before you stumble upon the solution. As penny-arcade described it, epiphany is the central game mechanic.

The story is as impressionistic as the artwork, mostly told in snippets of text that accompany the entrance to each world. They relate the mechanics of time in that world to the ways in which we experience events in our lives. One section describes how returning to a place laden with memories can cause us to feel as if we are travelling in time, and not just space. In that world, time moves forward as you move to the right and backwards as you move to the left. The story and the art both get darker and more mysterious as the game progresses, with a baffling ending that will leave you reevaluating everything you've seen up til that point, probably for days afterwards.

If there was any debate that games are an art form as expressive as any other, Braid has settled it.

You can get the PC version from several sites, including Steam, or the Xbox version from Xbox Live Arcade. All are $15, and a free demo is available.