I don't know what bar you're using for "mainstream", but if it doesn't include videogames in the late 80's/early 90's, it's too high. If being more popular than any other single toy short of a ball isn't mainstream, nothing is. Sure, they're even more popular now, and they may be more popular still in some areas of the world, but that doesn't make them not mainstream 25 years ago.

as reference, according to wiktionary, mainstream is Used or accepted broadly rather than by small portions of a population or market. I think that definition can encompass 40,000,000 households owning consoles.

To add to this: Skyrim sold 30 million copies. That's more than all but 7 music albums ever made.

Wii Sports (12 years old) sold 80 million copies. That's more than any album ever.

Individual videogames regularly sell more than MUSIC and have done so for well over a decade.

I don't know what definition of mainstream there is where something sells 80 million copies and still isn't mainstream.

comparing sales of specific video games to specific albums seems like a weird comparison. for every one purchase of an album, there will be many people who hear it without purchasing it (on the radio, in restaurants, while shopping, etc.). the only legal way to experience a videogame without purchasing a copy is to play at a friend's house. games like fortnite might rival the most famous pop stars today in cultural significance, but I don't think you could say the same for GTA vs Britney Spears in the mid 00's.

Wii Sports was one of the first mainstream games. That's pretty much the boundary of the two eras. Everyone at the time was talking about how the Wii was penetrating all these "mainstream" markets that gaming had never managed to touch before, remember?

Tetris has sold 170 million copies.

Super Mario Bros sold over 40 million copies.

Both of those games are 30 years old. Wii Sports was not even close to being one of the first mainstream games.

The original Pokemon games sold over 30 million copies, inspired a massive worldwide TV show, and that was over 20 years ago.

I'm wondering if comments like this, that place "mainstream" somewhere in the mid 2000's, are being made by people born later, who grew up with ps2/gamecube and then wii console gen. They strike me as not being very familiar at all with the actual success and market penetration of videogames before then.

You cannot compare games to music unless you include all licensing revenue for radio stations, films etc. I don't own a single Beatles album but I still know a lot of their songs.

Videogame revenue surpassed the U.S. movie and music industry in 2005 and 2007 respectively, including all licensing.