Eternum (warning: NSFW) is an adult visual novel that keeps touching me with every new update. It's completely free, and I can't help but think of the creator as a master of the genre.
The characters are all well written and (those who are meant to be) lovable. The story is interesting, compelling even, and the humor is often hilarious. When you go to the website, you might think "Porn game!!!", and not be entirely wrong, but Eternum is so much more. It's a story about love, friendship, and a mystery.
Setting: Orion moves back to the USA after a long time. In recent years, a video game called eternum has been gaining traction, that allows going into virtual worlds, think full dive VR like in Sword Art Online. I'd say about 60% of the story happens IRL.
I can only recommend this masterpiece of a visual novel.