Mindxpander

Mindxpander is a simple memory game presented in text-mode. You're presented with a 4x4 grid of 16 numbers. You have 5 seconds to memorize their positions. Then one of the numbers is covered up, and you need to type it in. Then you can keep playing to try to increase your score and/or memory capabilities. It's not easy (at least not for me) and seems to be partially luck-based, since it seems difficult for a person to actually memorize the positions of 16 numbers in 5 seconds. But if you want to work on your memory, maybe this will help?