If your real interest is how many people bought and played Half-Life Alyx, some back-of-envelope math gives us some pretty reliable estimates (assuming SuperData's numbers are also fairly reliable):

Half-Life: Alyx performed modestly by the standards of AAA games but was a blockbuster by the standards of virtual reality (VR) exclusive titles. A total of 860K gamers played the PC VR title in March. The game had a limited addressable audience, as there was an install base of fewer than 4M PC-compatible VR headsets at the end of 2019. Direct purchases of Half-Life: Alyx generated $40.7M in revenue, and hundreds of thousands of free copies of the game were also bundled with devices like the Valve Index headset to boost interest in VR.

New revenue report from Nieslen analyst firm SuperData* has some very interesting data for people following MMOs/virtual worlds and VR, especially in the wake of Valve's first VR-only game:

If Half-Life Alyx made $40,700,000 from direct purchases at around $60 a copy, then it's sold roughly 678,333 copies so far. (Round that up to 680,000.)

If 680,000 people bought a copy of Alyx, subtract that number from the 860,000 total players of Alyx that SuperData restimates, and that's about 180,000 people who played the bundled version on the Valve Index.

So roughly 1 in 4 people who have the hardware to play Alyx, played Alyx, and roughly 1 in 5 people who have the hardware to play Alyx if they pay for it, paid for Alyx. I actually guessed it would be closer to 1 in 2, but maybe it'll get to that level toward the holidays.

As for the other top grossers of March 2020 (see the chart), it's notable that almost 1 in 6 of the top hits are either MMOs (Fantasy Westward Journey Online 2, World of Warcraft West, World of Tanks), or virtual worlds/virtual world-ish: Animal Crossing, Grand Theft Auto V, Fortnite, and Roblox).

* Yes, yes, some readers tend to be critical of SuperData's numbers, but as a Nielsen property, it's the de facto industry standard, and by my lights, provides the best (or least worst) estimate of numbers that publicly traded Facebook companies mysteriously refuse to report in detail.