Sherlock Holmes: Crimes & Punishments, especially The Kew Gardens Drama.

Im not solving anything :D just my life :D but still want to win :D

As a kid I remember playing KOTOR2 and feeling a sense of elation after clearing that doctor's name for the murder on Onderon.

It's not a particularly great mystery but the amount of frustration, time I sunk in after school to find the right dialogue choices made it memorable I guess ha.

I just finished Return of the Obra Dinn and so I think that was most memorable.

It has to be either or both of werewolf-related side-quests:

Witcher: Beauty and the Beast, this one stuck with me because the story line of this quest is so interwoven with main story, it seems it is always in the background.

Witcher III: Wild at Heart, this stuck with me because it was the first high emotional point for me when I have played this monster of the game. And it also stuck with me, because I was still a bit weak to fight the werewolf when I attempted it, so it was really intense battle.

They are both multistage quests, that subvert expectations, masterfully written and perfectly fitting the game world.

The “Bridge to the Turnabout” case in Phoenix Wright: Ace Attorney - Trials and Tribulations.
Really involved and twisty.

I solved the biggest ever global conspiracy and came out alive in Deus Ex Human Revolution and Mankind Divided.

They couldn't stop me getting the truth out!!

Did I really solve Her Story?

I thought I did, but the game refused to judge me and I was pleased by that freedom. For days afterward, I indulged my doubts and mulled over the case.

A lot of notes were scribbled down during my playthrough. I still have that page. It's an amusing record of how my train of thought derailed over the course of the game.

Few experiences have been as strange and memorable.

Gabriel Knight: Sins of the Fathers

To solve the case your character needs to use both social and analytical skills, as well as his natural charm.

High attention to details is required, however the game does not annoy you with pixel-hunting. You often rely on cunning and masquerade to interrogate reticent suspects.

Nevertheless, main character cannot do every task on his own. Sidekick's help with research and gathering information makes the story much more realistic.

The investigation is full of false leads, which distract you from the main suspicions and question, if already made conclusions are actually valid.

While some of the results are easily predictable, the story can offer many surprises as well. And you still need to find enough evidence to support your theories.

During the case you tamper with encrypted communication, either transmitted in audio form or scribed using runes. That can become real challenge for player's logical skills.

You are never sure if your disguise really works, or an adversary merely waits for a good moment to strike. The game becomes very intense during infiltration missions.

Main character can be killed if player acts carelessly or does not prepare enough for risky quests. You actions have delayed consequences and make you feel responsibility for placing other people in real danger.

Game presents hints for puzzles that will occur much later in the storyline. They do not make much sense right away, but when you recall these hints later, you realize how well interconnected the entire plot is.

The only disappointment is university professor's death, which is an overused trope, and therefore diminishes an overall immersion.

Intensity of the story is complemented with really good humor and many well-written dialogues. Original soundtrack is absolutely amazing and makes locations very atmospheric.

On a way to the solution of the case, you are introduced into a rich cultural background of New Orleans and can learn a bit French in process. Visual novel based on the game brings additional depth to the backstory.

All in all, Gabriel Knight: Sins of the Fathers offers you one of most interesting and highly detailed criminal investigations in video games.

The most memorable criminal case which I ever solved in a video game was probably Autumn Leaves story mod for Fallout: New Vegas. Story was about vault, which was one large library and was up to player to solve mystery of this vault.

Solving my own murder at Murdered: Soul Suspect was pretty weird :D

I, The Player, have not taken these cases on, despite having them both backlogged. Thank you for the suggestion as I, The Player, should take these cases on.

Thank you for the reminder, my fellow Gumshoe.

Solving the murder of the king's soldiers in Romney with a spyglass and a spider as clues in Betrayal at Krondor.

Haven't played many with similar quests, but i do remember solving the case in Sanctuary in Borderlands 2