If you're over 40, you may not have all the latest electronic technology down pat. I'm 61 and I don't even understand half of what my sons, both in their mid-30's, are talking about when they're in their techno talk mode. But I keep my mind sharp by keeping up with a few techno hints of my own.
Tetris - Tetris is a fun, easy to learn game I bought on the Internet for under $10. I think they even sell them at toy stores in game boxes. Basically, Tetris has colored blocks that in different shapes that move from the top to the bottom of the screen. By using directional arrows, you turn the blocks to fit each other like puzzle pieces. You earn points and when the screen fills to the top, the game is over. While I started out with pathetically low scores like 3,000, I quickly moved to 30,000 and above, learning how to move the blocks left to right, right to left; to rotate them; to fill the lines, not leaving any blank spaces. There are several different games you can play with Tetris but I stick with the basic game, just improving my score as I go along.
Scrabble - I've been a reader all my life so words have always been fun. You can buy a travel Scrabble game or you can buy an online game. I think mine cost about $20. Can't sleep and don't feel like taking a sleeping pill? Well get up and play yourself on the Scrabble board. The computer will let you play another person but it will also let you play the computer. And you can choose the level of expertise you want so you don't feel like the computer is constantly beating up on you -- or that you're beating up on the computer, getting bored because there's not enough challenge.
A site called Orisinal has loads of games, just pick one that's fun for you. I love one called the Daring Dozen. I have to shoot an egg from a basket, into another basket moving across the screen above me. I go from basket to basket. When I miss, my egg drops and an egg disappears from an "eggboard" at the top of the screen. The game is over when you've lost all the eggs from the eggboard. Challenge yourself to get higher scores and increase your eye-hand coordination.
Keeping your mind sharp is no longer a chore. Computerized games make it fun and easy. And even an hour or less a day will bring some increase your memory retention. Happy gaming!