It's a few years old, but I was blown away by Astartes. Sure, the lore is a bit dense so I didn't fully know what was going on, but the story was well crafted enough that it kept me hooked (and all without any real dialogue). More importantly, the animation, VFX, SFX, and direction are all astonishing. As in, easily Hollywood level (and noticeably better than a lot of Hollywood sequences). And it's all been made by one person (mostly). I can see why Games Workshop have actually brought it into canon.

(Coincidentally, this is how you do brand control. Fan makes amazing thing, community embraces it, you embrace it. One day fan film takedowns will be a laughable joke of an ancient mindset 🙄)