Age doesn’t matter when you are talking about a fun puzzle games.

User Rating: 8.8 | Mario no Picross GB
I played this game 10 or so years ago and still remember the huge amount of fun I had playing it. You can save your progress in one of three sections. It even has a “how to play” section if you need it along with Easy Picross and Picross to choose from. The next screen has three choices and they are Kinoko with a picture of a Mushroom if you click this one it brings you to all the problems for this section. What is nice is that as it runs from 1-8 and A through H it also keeps track of your first time, how many times you have done the problem, and your best time. The second section you can pick is Star with naturally a star with just as large section to do and the same saved stats as the Mushroom section. The last choice to pick from is called the Time Trial and if you beat the times listed you can add your name.
Now to try and describe this game. First of all there is a grid of 15 squares by 15 squares and within these squares they are divided by 3. This helps so with a thicker black line it is easier to count by 5’s.
Each line whether it is diagonally or horizontally will be numbers like 3, 2 which tells you how many boxes you need to chisel in that particular direction. So 3 mean a grouping of 3 and 2 means another grouping of 2 that should not be there.
As you progress through the game the puzzles naturally get harder and larger. The numbers can eventually look like this, 2, 5, 1, 4, 2, 1. You can see that it can get complicated but it is so much fun. I would just turn off the music, but it is up to personal taste on how much tinkling you can take.
Other fun puzzle games of this age are Boxxle and Kwirk.