Daggerfall Unity is the open source game engine built with Unity for running the 1996 classic The Elder Scrolls II: Daggerfall and it's coming along very nicely.
A new release just went up with Daggerfall Unity 0.10.28, which the developer mentions is now "feature complete" and so it will be moving from Alpha to Beta status soon. Going by their roadmap, that sure is a lot of completed items. It's not finished though, as they will move onto bug fixing, minor adjustments, modding, translations and so on.
What's new with this release? Large HUD support, along with the ability to have the HUD docked or undocked meaning it can either stretch or have a more fixed size - good for bigger resolutions where it might get too stretched.
There's more ways to configure the HUD now in the settings file too, and a big overhaul to the movement system to better match the original. They can't match the movement system exactly, instead going for a system that enables you to feel more powerful and faster when you're a higher level. The biggest change appears to be the jumping ability, with it now giving small jumps to low levels and bigger / longer jumps for higher levels.
Plenty more smaller and varied fixes also made it in, there was a lot of little bits of fine tuning.
Since it's such an old game, it's also freely available as Bethesda Softworks put it up as a free download back in 2009. This means it really can live forever with an up to date cross-platform game engine. Daggerfall Unity isn't quite the same though of course, as it does have some unique enhancements so it's more like "Classic Daggerfall Plus" as the developer calls it.
Looking to play the later game, The Elder Scrolls III: Morrowind, with an up to date and open source game engine? Try out OpenMW too! It's quite awesome.