What's the most immersive video game that you've played?

Haven't touched it in years, but there was a mod that converted all player dialogue to voice commands. Meaning that when you were talking to an NPC, you actually spoke the words you wanted to say. That, with the verbal dragon shouts, and gesture activated spell casts... Good times.

Best part is that your normal Skyrim mods generally work just as well with VR Skyrim.