Virtual reality for the lady sadist is appealing to her extreme and cruel nature. Like anything else, practicing sadism comes with its frustrations. First off, It is hard to find an actual slave that submits to your every desire. And second, complete satisfaction is impossible due to the unethical and extreme nature of some fantasies. For this reason, a limitless video game would be ideal and fun for a woman with cruel intentions.
In an ideal video game for my sadistic desires, I would be able to choose my slave from a line up of men or women. My selection based according to looks, age, education, and stats such as real-life job titles. I would even be able to set the threshold for the level of my slave's compliance. Ideally, I could design my avatar. I would be able to dress it too. The clothing options would include leather and latex, along with other fetish related clothing.
After picking your character and slave, you get to build a dungeon. You would be able to earn coins through the suffering of your slave. The more it suffers, the more coins you get. Use your coins to purchase more BDSM equipment or expand your dungeon. You can even buy another slave.
Be creative with your torments. Make them masturbate with salt or toothpaste. Or have your subject edge and then ruin the orgasm. For those of us who are into the more extreme, performing Lingchi isn't out of the question.
Imagination is your only inhibitor. The slave can bleed and suffer indefinitely but will never die. It is yours to torture relentlessly for as long as you please. Perhaps, virtual reality for the lady sadist is ahead of its time. As VR technology expands, I am sure these games will be in demand.