Below you can see footage which has been submitted to us anonymously by one of our readers. We've been told the video shows a build from 4-5 weeks ago, of the Source reimaginaging of Half-life 1 chapter 'On a Rail'.
The BMS team have published this official statement, answering many of the questions you might have.
The video shows several iconic Half-life 1 weapons with a couple of mechanics which seem a little out of place in Half-life (iron sights!?). Nonetheless, it's good to see some gameplay footage of the mod which is as elusive as the loch ness monster.
Info on the video changes and current situation here.