Since Sense 3.0 was released, HTC had its own theme engine built in, using a proprietary format. Why they used a proprietary format no one knows, but they did. Luckily, two devs by the name of Flemmard and Diamondback found a way to crack the format. With Sense 3.5, HTC changed the format (again, why is HTC so anti-modding?), but they managed to crack it again. With Sense 4, you guessed it, they changed it again (if they let you bootloader unlock your phone, why does it mean so little?!). Luckily, a dev named cypis cracked it this time, creating the first custom theme for Sense 4.
Just like the built in themes, Virtuous Immersion themes all areas of the phone, including the stock launcher, Sense apps, and lockscreen (of course you have to be using all of the stock apps for that). It’ll work for any Sense-based ROM, unless it’s a lite version. But in the end, this just opens up new possibilities for themers and modders everywhere. Our phones just keep getting better and better.