In my expert opinion, the short answer to this question is: yes, no, absolutely.
Before I delve deeper, I would like to applaud Brenda on astutely listing these games in chronological order based on their US release. Pong debuted in 1973, Below the Root in 1984 and Tetris in 1987. Holy throwback, Batman.
Pong is generally considered the first successful video game on the market. It proved that games like these could make money. Pong first hit bars in the form of huge bright yellow arcade cabinets thanks to Atari.
Do people still play pong? Yes. Atari has a Pong pack available as part of it's Greatest Hits for mobile devices and the cabinets are still around. The hubs and I played on one a couple of years back at the Strong Museum. Just tonight, I played a version at ponggame.org (presumably a version very close to the original as it kept freezing on me.) Regardless, I highly recommend you reminisce. And, if you have never played Pong before, by all means, now is your chance.
On to Below the Root. It was released on "flashback floppy" for IBM PC, Commodore 64 and Apple II. Categorized as a single player adventure game, it was based on a trilogy of novels written just a few years prior. I am pretty sure Brenda may have been the only person to play this game, but if that were actually the case a lot of people missed out. It seemed fairly intricate for 1984. For instance, you could choose to play as one of five characters (of two separate races) each with different abilities. The graphics weren't bad for their day either. This is what the game looked like:
Do people still play Below the Root? Brenda has an iPad now so my guess is no.
Time for Tetris! I love Tetris. My passion was renewed just tonight when I played it again for the first time. Born in 1984 in Russia, Tetris came to American PC's in 1987. Then, in 1989, Nintendo (who by then owned the exclusive handheld rights to the game) bundled their brand new Gameboy device with the classic (and sold 35 million of them.)
As soon as I uttered the word "Tetris" tonight, the hubs was up the stairs (and back down) in a flash, both original Gameboy and Tetris cartridge in hand. Game on. Well, first he had to gingerly remove the acid coated AA's. And then he realized he had grabbed Metroid by mistake (or was it?) Long story short, I played Tetris tonight! Twice! My high score was Level 11 and 34,847 points. As crazy as it may be, as soon as I post this, I might enjoy another round. The juxtaposition of playing Tetris on the original Gameboy while my husband plays Skyrim on the 360 is kinda groovy.
Do people still play Tetris? Abso-friggin-lutely! They also still play "Korobeiniki" the 19th century Russian folk song more popularly known as Type A Tetris Theme Music. I found (and listened to) renditions on the following instruments: piano, ukelele, laser harp, church organ, glass bottles and cell phone. Then there is the rock remix. Ah, the internet.