In the crazy alternate universe where this mod comes from, Half-Life has snow zombies. Also, instead of Alyx, there's a trash-talking robot buddy who looks like a dustbin with wheels on it. And there's penguins! You can see one in the screenshot. I think you're aiming a harpoon gun at it.
The mod is called ICE, and if its Mod DB page is anything to go by, it has been in development since January 2013. The official summary describes the story and setting:
Continue the incredible Half-Life 2 storyline somewhere in the Antarctic through ice landscapes and underground bases inspired by Half-Life and conspiracy theories like the "Dulce Underground Bases" and the "Nightmare Hall" all in the comfort of a new MKVII HEV Suit.
The two guys behind the mod, Jason Snell and Timian Ba, have released a short teaser, partly to show off their progress, and partly to try and recruit some extra help with textures and animations. It's more of a proof of concept video of an obviously incomplete project, but it really shows the difference between the main games and this mod. Here, it's more about goofy balls-to-the-wall action than Half-Life's perhaps more reserved horror-sci-fi action. Take a look:
The mod is about 60 per cent complete, according to the latest Mod DB news post, and there is currently no ETA. If you're interested, keep an eye on that page. This has the potential to turn into something really fun.
ICE - A Half-Life 2 Expansion Pack [Mod DB]