I am currently playing Enderal a free total conversion mod which offers a totally new RPG using the Skyrim engine.
It is great. Not just great for a mod or a free game. It is just great. The story is great. The quests are great. The graphics and sound are great. The voice acting is great (even in English translation). The game is remarkably stable and bug free. How did they achieve all of this on a budget of zero euro? I have no idea.
If you have Skyrim (any version) then you can download Enderal here in either English or the original German versions. You need to download both the installation package and the launcher. Put the launcher into your Skyrim directory (probably C:\Program Files (x86)\Steam\steamapps\common\skyrim). Run the launcher and hit "install now". Navigate to the installation package when prompted.