Try using a xbox controller for HL2 , then you can control your speed and it allows you to turn around and not worry about where the keyboard is - Oh and standing up helps with the immersion , well for me anyway - Definitely try titans of space and a short one called Malfunction - Am so waiting for the next version of this , it still blows me away every time i use it
So this is the best thing ever. Not really done much with it, a couple of rollercoaster tech demos (I actually felt like I was being pinned back in my seat, weird), and the 360 degree first person porn film, natch. But I also tried Half-Life 2. It's completely unplayable as a game with KB/M, as you have to use the mouse for sharp steering otherwise you'd end up facing away from the keyboard, and it throws your alignment off, but that aside, just walking along the train, through the station and up to characters, looking around at the world, is truly astonishing. The 3D effect is more convincing in this than any of the tech demos I tried. To make it actually playable beyond the intro I'd need a Razer Hydra or similar, but there's only one on eBay and it's already at £90 with three days left :-/
The resolution is quite jarring, and the doorscreen effect is noticeable but soon disappears, but despite all that it offers a level of immersion that is quite unbelievable. A version with a proper screen is now my most needed thing. Next is to play more than 10 minutes of HL2 and actually get out of the station, and try the Portal mod, which may make my head explode.