The countdown to next week's release of Portal 2 continues and, in this day of digitally delivered games, there's no better sign that it's really happening than this: the pre-load. For those of you eager to return to Aperture Science and reacquaint yourselves with GLaDOS as soon as possible, buy the game on Steam and get that client downloaded.

Speaking of downloading things through Steam, if you purchased the Potato Sack bundle -remember, "13 hit indie games, 75% off"? - you can expect many of those to prompt you for an update. You see, Valve and those sneaky indie devs have been planting Portal 2 hints all over those games; today, things get a little more explicit.

Bit.Trip.Beat (above) has a Portal 2-themed level, GLaDOS and all; Killing Floor (gallery below) has some Portal 2-themed environments; and The Ball has seven new "test chambers" featuring the "Edgeless Artifact Cube." Also updated: Wonderful End of the World, Cogs, Defense Grid, RUSH, AaAaAA!!! - A Reckless Disregard for Gravity, AudioSurf, Amnesia: The Dark Descent and Toki Tori. You'll find a video of Bit.Trip.Beat in action after the break. Got a video of another updated game? Share it in the comments and we'll update this post.