What's a virtual reality headset without software? Nothing -- and Sony knows it, which is why the company is treating GDC attendees to four demos on the conference show floor, starting tomorrow morning. Some of them are familiar: when EVE: Valkyrie was announced as a playable demo, Sony's GDC audience erupted into cheers and applause. Gamers stopping by Sony's booth will also get a chance to play a special build of Thief created specifically for virtual reality. Although these traditional gaming experiences are likely to steal the show, Sony's also trotting out two demos that sound more passive: The Deep and The Castle, which lets players experience a shark-infested lagoon and a medieval fortress, respectively. So, how do these games play? We'll let you know as soon as the GDC show floor opens tomorrow.