When I was growing up I was a huge fan of Tetris. In fact, everyone in my family was. I had the original Nintendo, and we’d fight over who would get to play it. My Mom would even get into it. There are lots of clones around and web-based Flash versions. A very good one is N-Blox.
The same site also has several other classic arcade games such as Frogger, Space Invaders, and Asteroids. Visit Neave Games to see and play them all.