At GDC today, Valve has been showing off a demo of HTC's new virtual reality headset. We're going to see the demo tomorrow morning, but we already know a lot about it from our colleagues' reports: it looks a lot like a new Portal. It is not a new Portal.

I reached out to Valve and asked for a comment on how the demo is being interpreted: CNet, for instance, said it "sounds like" Portal 3, while Tom Parsons of Stuff claimed that he had actually played a Portal 3 demo during his Vive hands-on. I told Valve that I was skeptical that they'd soft-announced Portal 3. Valve director of marketing Doug Lombardi responded, "We have not."

I followed up to be absolutely clear, asking, "The demo being shown does not represent a prototype or indicate any plan for a new Portal?" Lombardi replied, "Correct. Just a demo." So no, this isn't Portal 3. It's just a tech demo until we know more—and I suspect Valve is just having fun with some existing art.

The above trailer is the work of Portal 2 machinima-maker 'Harry101UK'. The mod powering it is Portal Stories: Mel. It's a new story, based in the Portal 2 universe, about new protagonist Mel and the new personality core that she's travelling with.

The mod boasts custom textures and animations, and over 20 new maps. It's also been Greenlit—meaning it will be made available directly through Steam. And, unlike last year's Aperture Tag, it will be entirely free.

For more, head over to the mod's Steam page. Portal Stories: Mel is due out early-2015.

If you search Steam for nothing and then sort nothing by user reviews you'll get a neat list of the most popular games on Steam among user reviewers, based on the percentage of positive reviews on the system. Portal 2 wins. Of 35,550 reviewers, 99% like the game. Make more games please, Valve.

If you prefer raw numbers, Dota 2 (94% of 280k users like it) and Team Fortress 2 (97% of 200k like it) come out ahead. Skyrim also does well. 98% of 78,842 users like Skyrim.

One Finger Death Punch, Crypt of the Necrodancer and Nuclear Throne have 99% positive ratings too, which is good, because those games are totally ace. In fact, the whole list is a brilliant resource if you're looking for ways to spend your spare Steam wallet pennies in the Steam sale.

Here's a shot of the top ten. What do you think?

Apart from a guard booth and a small shed in a field, most of what we've seen of Aperture Science has been carefully hidden underground. Perhaps if things hadn't gone so horribly wrong in their massive subterranean lab, Aperture eventually might have built a proper above-ground campus, like Google or Microsoft.

That's the premise of Above Aperture. You're on an excursion to Aperture City, a large above-ground compound littered with buildings and devious test-chambers. 

Yes, you're still as trapped as Chell ever was, but the open-air nature of most of the chambers and the little outdoor strolls you take between the challenges give it a different feel than the subterranean labyrinth we're used to. Aperture City, naturally, is abandoned and crumbling, and armed with only your wits (and a cool handheld device), you're trying to find your way out, or at least your way through

Above Aperture features some custom models and art, as well as a really nice piece of custom music. Not only are the maps lovely to look at, but they're pretty challenging as well. I spent a good deal of time in the very first level wondering just what the heck I was supposed to do. I could clearly see the spots I needed to get to, and I knew I had the tools to get there: my portal gun, a light bridge, and a faith plate. There were even clues in a few spots, little arrows painted on the concrete... anyway, it was a challenge, a nice twist on the standard game-play, and quite satisfying when I finally figured it out.

Light bridges are a big part of most of the puzzles, but there are other familiar elements: laser-beams and mirror cubes, a bit of gel, a few turrets here and there. The chambers are nice and big, and for me, they're the best kind: where you sort of wander around for a bit before you even try anything, peering at the walls and ceiling, trying to put the solution together in your head before you actually start firing the gun.

I really do like being above-ground, too. I know, it's just a skybox, and the maps may as well be underground anyway because you're trapped in them either way, but it still feels a bit more freeing being able to see the sky (though no moon, of course). It's also one step closer to my ultimate Portal dream: a huge GTA-style metropolis I can fling portals around in.

If you spot a radio during your travels, make sure to take it with you: there's a cool custom song hidden somewhere in the maps, and you won't want to miss it. (I definitely missed it my first time through.)

Above Aperture is in three parts which you can subscribe to here. I certainly hope there will be more of this adventure to come: the puzzles are pretty fiendish and the maps are very well designed, not just in how the puzzles function but in the overall atmosphere as well.

You can also check out more of the modder's Portal 2 workshop items here.