Awesome collection. I've thought about picking some up, but that would be a slippery slope for me - I'd end up wanting them all
Besides I don't find them particularly fun to play - it would just be a great thing to collect.
You have to have a motive to get into collecting this stuff.
Mine is: I love Nintendo, and found these intriguing. I wasn't in that time frame during the originals, but I did find things to get me interested.
When I was a kid, they had the Mini Classic games at places like Walmart. It was like "Cool, it's Nintendo, this one's Mario, this one's Donkey Kong Jr".
I also found the Game & Watch Gallery games as a kid. The box art depicting the Mario characters doing crazy things, so I got it because I thought it was a Mario game. I slowly learned about the Game & Watch franchise and tried collecting as many Mini Classics as I could.
I had more than 3 Mini Classics at one point. Some were lost, some were given away, and some were broken. I had 2 versions of Mario's Cement Factory, I also had Octopus, but I lost it during a move.
When I was a young teen I eventually asked my mom to get me an actual G&W on ebay for christmas. I got a used Super Mario Bros in used but decent condition. Next year I got Bombsweeper.
I started collecting them again this year.
As for the games themselves, they're mostly time killers. Think of phone games, with very simplistic graphics.
The gameplay ranges from game to game. A lot of them test your reflex. As the score goes up, the speed and quantity of things going on in the game goes up. It's fun if you're waiting for something.
Other games have more depth to them.
Super Mario Bros has 8 levels, enemies, and even power ups. Very impressive for an LCD game.
Bombsweeper is a maze puzzle game where you push walls to disarm bombs. This one has even more levels than Super Mario
Donkey Kong Jr is like the NES game but more simplistic.
When I was a kid, they were great to have. I could carry them through class and say it was a watch, and play them during break. A lot easier to carry around than a Gameboy.
Now I like to collect them, and I still play them when I'm in the mood to check a game out.