One of the earliest NES games, and possibly the first fighting game.

The idea of the game is to get your opponent (computer controlled or human) to fall in a manhole. This goal is accomplished by punching their lights out. Of course, your opponent has the same goal. So, to keep this game from being too unrealistic, you can block. However, if you could block without thinking, this would get tedious fast. To add some guesswork, they made high and low blocks, and similar punches, so that the excitement of fighting is reduced to rock, paper, scissors.

After this, fighting games would pretty much go nowhere until punch out.
And, oh yeah, theres a lady who trows flowerpots out the window to hit your head. Still boring.