With Garry's Mod, there are many custom game modes where you can role play as different jobs. Some examples are DarkRP and 1942RP where you can choose between thieves, drug dealers, doctors, bartenders, bakers, factory owners, wine makers, civil protection, soldiers, or whatever the server owner has designated as a job.
What makes Garry's Mod so special is that as long as someone has sufficient knowledge of lua and glua, they can literally make almost any game mode they can think of that is possible in the Garry's Mod engine.
A very popular server game mode nowadays aside from DarkRP and 1942RP is HogwartsRP. In HogwartsRP, people are able to role play as students, teachers, or death eaters of the Harry Potter series. Because the Harry Potter series is so well loved by both genders and multiple age groups, this game mode attracts both men and women equally.
Garry's Mod can basically appeal to anyone as long as the game mode they choose to play in or create is something they appreciate. The game generally goes on sale for $2.50 USD often on steam. I'd suggest to anyone that hasn't tried it even though the game is 12 years old at this point in time is to pick up a copy the next time they notice it goes on sale. I'm sure it'll be possible to find at least one cool game mode on there worth the small investment.