Long ago, while working on another game that I never finished, I stopped and made a quick & dirty version of Memory. I only just realized, more than a year later, that I stuck it in Work in Progress unintentionally!
Use the arrow keys to navigate the grid, ❎ to flip a tile, 🅾 to toggle show/hide the time clock (useful if you want to see how close you are to a personal best). When you match two tiles, they'll stay flipped. When you match all 16, the game is over! Try to see how fast you can match all 16 tiles. My personal best is 23 seconds, but I'm sure it can be done faster. I blame my arthritis for my performance :). If you beat 23 seconds, let me know in the comments!