Everyone knows Tetris, but do you know the original Tetris?
This is THE original commercial release of Tetris. That makes it something like the grandaddy of granddaddies. Its age is reflected in its technical limitations. The graphics are very old but are not aesthetically displeasing. The controls are unusual but not insurmountable. The only thing that might disappoint you is the lack of music - believe it or not, the world famous Tetris song is not present in the original release. Just try humming it while you play.
The age of the title is pleasantly reflected in the overall presentation. The Russian lettering and 'Top Comrades' high score screen are what give this game its charm. It may only be about twenty years old, but in terms of software that makes it an antique. This antique, however, is not only still usable (with DosBox, that is) but is a joy to play.