Hey, I'm a bit late... Yes the game has few options but all of them have drastic implications to the plot, if you try every choice you can have hours of content.
About mandatory anal sex, I chose to do it like this to diferenciate the character but in the next versions especially in romance route the Player can slowly turn the character (Coworker) into a "normal" girl.
I hope you keep playing the game and the next versions.
Thanks!