The Nether. Woah. Without giving too much away, it did a wonderful elegant job of transitioning between the real world and the virtual world that I thought was very well-done while being sufficiently understated to avoid having special effects be a focus. It's a disturbing play, in no small part because of the moral ambiguity. The temporal ambiguity was also handled well. It wouldn't be for everyone, since it may be triggery or overly disturbing for some, but I thought it was a powerful approach to real moral issues with an immersive virtual world and avoided being preachy. [Spoiler that amuses me]It also has distinctly the lowest character to actor ratio of any play I've seen. As long as we're not counting LARPs.
In related news, I really like the Seven Dials area. Lots of cool shops and, importantly, non-zero ice-cream density. Plus, it's a great name.