Grand Theft Auto: San Andreas

The game gives a variety of control options -- from a virtual analog stick to swipe gestures -- and has well-placed controls for other game features. This is optimal for tablets, but smartphone users might have too much on-screen at one time.

Explicitly sexual. Prostitutes are prominent characters in the game, both as part of the story and non-player characters -- and they're dressed in low-cut apparel, true to the streetwalker cliche. You can gain "health points" by having implied sex with a prostitute in your car, where you hear what's happening and watch the rhythmic actions of the couple from a distance but don't actually see the act. 

The game is part of a long-running franchise, and players may be moved to buy a more recent version of the game after playing this.