I'm not entirely sure what this is, exactly, but whatever it is, it's available for free on GOG.com. Apparently, it's a highly modded version of The Elder Scrolls II: Daggerfall (which is also available for free, along with Arena). I've played through that (the original Daggerfall, I mean) a couple decades ago, and it was pretty cool, if a bit dated (even back then, based on what I recall of it, because I'm pretty sure Morrowind was already out at the time I first played Daggerfall). Doubt I'll play this modded thing anytime soon, but it's there if one wants it, regardless.