Sports:
Traditionally, the sports category has always taken the largest piece of the pie when it comes to categories of games broken-down by percentage of sales.
In the past, I have worked on games for nearly all sports genres: Football, Basketball, Baseball, Hockey, Soccer and Boxing, many of them during the early '90s at Park Place Productions, developed for several gaming platforms with Sega Genesis being the primary gaming console at the time.
Below is an example video someone posted on YouTube of the game Muhammad Ali's Heavyweight Boxing for the Sega Genesis and this game was quite successful. I actually met Muhammad Ali at the Consumer Electronics Show in Las Vegas and he autographed a Boxing glove for me. I was the only programmer and this product was developed entirely in 68000 assembly language using a RAM-based ROM-u-lator (EPROM emulator) before being sent to Sega to be burned onto the actual chips put into game cartridges.