The valve index is the latest VR headset and controllers from Valve. Now previously Valve partnered with HTC to make the Vive and the Vive pro headsets and the wand controllers which used Valves lighthouse tracking system but this new headset is made by Valve alone.
The tracking system for the headset and the controllers is the same Lighthouse system as used in the vive or vive pro and it is backwards compatible with the original lighthouse mk1 system that came with the original vive or the lighthouse mk2 which came with the vive pro.
The index is basically two different things the head mounted display and then the knuckle controllers which have been floating around in prototype for ages.
One great thing is that because the headset and the controllers all use the lighthouse system they are compatible with the existing Vive products and they will be selling all the bits separately. So if you have a Vive (like I do) and just want the new controllers those are available separately for 279 dollars. If you just wanted the headset to use with the old wand controllers and existing lighthouse setup you can do that and it's $500 for just the headset. You can also get the lighthouse 2 base stations separately but there isn't much difference in most cases to version 1 lighthouse (bigger rooms are supported I think)
They also offer the headset and the controllers in one package for $750 or if you want the full setup with lighthouse 2 base stations for $1000. The ability to upgrade piecemeal and compatibility with existing stuff is great, I really want the knuckle controllers but I'm not sure I'd want to buy the headset as I already have the wireless vive and I already have lighthouse mk1 stations. So being able to just get the bit I want is nice.
It features two 1440x1600 RGB LCD panels with 120hz refresh (and an experimental 144hz) over the ear built in headphones as I said it uses the existing lighthouse room scale tracking system.
The Knuckle controllers strap to your hands but leave your fingers free to grip and it senses finger movement and has a trigger button. They've replaced the big touch pad with a smaller vertical one and a thumbstick and a few buttons it's a bit more conventional and more like the rift's touch controllers but taken a step further.
It looks like a compelling upgrade with better resolution higher refresh rate some new controllers but with backwards compatibility so existing vive owners can upgrade piecemeal if they want. Pricewise I thing it's a little on the high end their major competition is going for the 400 dollar mark for their various products some of those are less powerful and feature more restricted tracking systems but still for someone coming in fresh 1000 dollars vs 400 is a bit of a jump.
There are a lot of VR systems coming up with the revamped Rift S the new standalone Rift Quest and a few other things floating around. VR is still a high end somewhat niche thing and it's interesting that the two major players seem to be going in opposite directions with Valve focussing on the higher end pc stuff and then Oculus pushing into the mobile space more and more. It's also interesting that Valve are pushing this one themselves rather than going with someone like HTC.
One other thing I've seen mentioned is Valve are promising a full VR game sometime later this year but details on it are absent except that it will presumably be tailored for the Index. Portal 3 vr maybe? Half Life 3 VR? Left 3 dead? One can dream