I was thinking today about how complicated technology is these days and how it both complicates and eases our lives at the same time. The younger generation grew up with computers and it seems to have really shaped their view of the world. They can't imagine life without them. The older generation struggle to keep up with changing technology; they even struggle to learn how to use a smartphone. All this happens while games like Tower Defense exist. It's an ideal game to help keep the mind sharp and focused, which is just what is recommended for many seniors.
The newest phones are made for game playing. The large screens, and touch sensitivity really facilitate fast fingertip action. With Tower Defense you need to be able to act fast to save yourself from invaders. As the Creeps invade, the game requires that you build towers and a maze to keep them out or trap them.
PCs are still a good tool for game playing but phones certainly are the best. Touch screen technology does exist on some PCs but it is much more awkward moving around players and setting up defenses on a large screen. So, grab your phone and start playing if you want to keep your brain nimble.