Fallout: New Vegas (2010)

In a random encounter three women are seen dancing in a fountain in their under garments outside a casino. A soldier scolds them till the women run across the street into the other casino.

In an (optional) side mission the player character is instructed to recruit three individuals to work as prostitutes for the "atomic wrangler" casino. One of them is a robot named "Fisto" referred to as a "sex bot", a man, and a zombie like ghoul. This can be very weird or uncomfortable to the player. Also upon completion of the quest the player can engage in their services.

An (optional) side quest deals with freeing several people who're forced prostitutes.

There is a crier in the freeside neighborhood urging the player to visit the "Atomic Wrangler" casino. She is seen dancing provocatively on the corner in an outfit that shows a lot of skin. She also may ask the player if he/she is horny and direct them to the casino.

The player can recruit a sex bot named FISTO, and he'll ask that the player "assumes the position", and will literally fist them with a black screen. During this short sequence, gears will be heard, and he'll ask if you liked it. One of the responses the player can tell him is "I can't feel my legs". This's purely for comedy and not to be taken seriously.

In the westside neighborhood of New Vegas there's a place called "casa madrid apartments". It basically is a brothel, there's a pimp, and three prostitutes (a woman, an elderly lady, and a homosexual man) which the player is able to pay for (offscreen) sex.

"Sarah" (the woman who runs the Vault 21 hotel on the strip) lets you choose one out of a few rewards for finding and giving her the Vault suits she wants. One of the rewards is to have sex with her.

"Red Lucy" from "The Thorn" located just outside of the west side neighborhood of New Vegas can give the player a side quest and upon completion the player has the option to have sex with her. The player can also come back whenever and however many times they want to have sex with her.

A few locations/characters offer sexual encounters, although everything is completely offscreen (and completely optional). Also there's no nudity but a couple possible instances of very revealing outfits.

There's "Gomorah" a casino and strip club with dancers, although they're only partially nude. There are also prostitutes including two "Joana" and "Dazzle" that can sleep with the player.

In a couple locations, loud sexual moans can be heard in the background. (Hard to hear, and lead to nothing. If you're not listening hard, you'll probably miss them).

There are prostitutes on the strip in revealing outfits, they can't be hired but they can and will say something flirtatious.

The player character can be disrobed, leaving them in (very modest) underwear. As well as dead enemies and any dead npc's if you take their armor.

If you play as a female Courier, and you have the "Black Widow" perk, you can sleep with Benny, the man who shot you, almost killing you, but he makes funny jokes while you have sex with him. And you can either kill him in his sleep and take his things, or let him live and have one of the Mojave's greatest factions, Caeser's Legion; a Roman War-based faction, take him and either kill him yourself when you find him, or let them crucify him.