Most of my videos have almost exclusively featured independent head and weapon tracking, and while this isn’t technically a requirement to play with the mod, it’s definitely the most fun and immersive way to play through the mod.

This guide will take you all the way from “that video looks interesting” to playing it yourself if you’re willing to buy the necessary components. This tutorial does make the assumption that you have an Oculus Rift as your HMD which should work out of the box with the mod for head tracking. Don’t let the length of this deter you, once you have everything initially set up, the actual process of playing the game is as simple as pushing the button on the controller, starting the game and putting on your rift.

The Hardware

In addition to the Oculus rift, you’ll need a handful of off-the-shelf (or internet) bits of hardware to get the mod working with independent head and weapon tracking.

The Gun Controller

I’ve tried a handful of gun controllers but the so far the only one that’s been cost effective is the xbox 360 version of the Top Shot Elite. You can pick it up for anywhere between $40-50 typically. You’ll also need an xbox 360 controller wireless adapter if you don’t already have one, they typically run for around $15 online.

The controller should be plug-and-play and is recognized by your computer as an xbox 360 controller. You won’t need the infrared bar or the scope since the tracking so you can toss those out.

The Tracker

In my initial build (and videos online) I used Hillcrest Labs FSM-6 trackers, which are the same one that John Carmack used in his doom 3 rift demos at E3 last year. They cost $100 initially run at 120hz but you can get the 250hz firmware upgrade from Hillcrest. Unfortunately while the tracking is plenty responsive the FSM-6 only has a gyro and accelerometer but lack a magnetometer that allows it to keep a consistent directional orientation which doesn’t matter much when using a single tracker, but when using head and weapon tracking this frequently causes the gun to drift horizontally. While I’ll continue to support the hillcrest trackers for people who already have them, I wouldn’t recommend buying it at this point for VR applications.

I’ve recently migrated both my head and weapon tracking over to YEI 3-space trackers. With an update rate of 1000hz and a magnetometer that prevents drift between the two trackers, it’s a major improvement over the Hillcrest without costing much more. You can purchase them from their website http://tech.yostengineering.com for anywhere between $100 – $170 for the USB version. For $100 you’ll get just the actual chip and need a bit of soldering know-how to attach a micro-usb connector, but the more expensive version comes in a very consumer-friendly form factor with a mini-b connector. You’ll also need a usb cable for the tracker, I use a thin 15 ft usb mini-b cable, but depending on your setup you may need more length. You’ll also need to install the 3 space software package available on their site which includes the drivers.

Attaching the tracker to the gun is pretty trivial, I’d suggest having the tracker facing up with the usb port toward the back of the gun. You can just electrical tape it to the to gun-site rail with electrical tape like I did or I’m sure there are plenty of fancier ways to attach it.

So now that you’ve got your tracker mounted and plugged in, assuming you mounted your tracker oriented the way I mentioned above, the last thing you’ll need to do is adjust the orientation using the 3-space sensor suite. Start the “3 space suite” program and connect to your device using the drop-down on the bottom.

Go to Sensor -> Advanced -> Settings and adjust the axis directions to match the highlighted settings below. After saving don’t forget to commit your settings before exiting the main app (I’m pretty sure that’s necessary).

Ok, you’re through the hard parts, now it’s time to install the game.

The Software

To play the mod, you’ll need to have Half-Life 2 (and the episodes if you want them to work) installed and you’ll also need to install the source sdk 2007. Aside from that, download the latest version of the mod and run the installer. Once it’s through, you’ll need to restart steam to see the new Half-Life VR (and ep1 & 2) entries in your game list.

If you start up the game with the gun controller on, my default controls should already all be set. Feel free to remap whatever Here’s the general layout:

Left Stick – Movement (sprint when clicked)

Button Beside Left Stick – Use

D-Pad – Up and down cycle weapons, forward is last weapon, backward is gravity gun

Button Behind D-Pad – toggle crouch

Right Stick – turn left and right in addition to the head tracking, you can bind up and down to things if you like but be aware, you’ll likely trigger them accidentally when turning

Click Right Stick – recenters the weapon horizontally with the view (this was much more necessary with the hillcrest trackers, but you’ll still need to do this initially on first load since I’m not currently saving off the calibration data so you’ll want this to be handy)

Left button behind the right stick (jump)

Trigger – fire

Pump – secondary fire

Reload – ‘back” or select button on the clip (I personally like physically having to do sort of a reload movement,but it’s definitely not the most efficient place)

Flashlight – start button on the clip

When the game loads a map for the first time, depending on how you mounted your tracker you’re weapon on-screen will likely be oriented incorrectly. Make sure your head and weapon are both level and facing the same direction and press the “L” key. Everything now should be all set for you to start playing.