Valve has released a short video demonstrating how Half-Life 2: Episode 2 extra Portal will work - and you can watch it on Eurogamer TV now.
We're also told to expect a new video of Episode 2 by the end of the week, with footage of Team Fortress 2 expected to make an appearance tomorrow.
Those of you familiar with Narbacular Drop - one of the games featured in yesterday's freeware games round-up feature - will already have an idea of what to expect. You move around Half-Life-styled environments using a special weapon to create linked portals.
In this way you can navigate otherwise impassable environmental obstacles, cripple enemy weapons and even create amusing infinite loops.
The video walks you through how some of this will work, and although it's a bit slow-paced to begin with, it quickly picks up after the first example - and ought to have you reeling by the end of it.
Portal will ship with Half-Life: Episode 2 - hopefully later this year if Valve's estimates are accurate - along with Team Fortress 2. It'll appear on PC, Xbox 360 and PlayStation 3.
For more on Valve's recent Episode 2 announcements, head into the blue.