I think it's QQSP or smth like that. You essentially get menus with areas, a "window" with your character, and these areas have sub-areas (like the city center has a mall, modelling agency, strip club, dance club etc), and you can do different things in these areas. You have (toggleable) needs like hunger, hygiene etc. So essentially you can do anything. Wanna work as a store clerk? Go ahead. Wanna be a stripper? Sure. Wanna be a street prostitute? Go to the right place and get to work, etc. Eventually you unlock "new" areas like the porn studio, and there is a storyline you can follow, characters you can meet and form friendships or relationships with etc.