I went on my steam profile (note these are all PC games, but some are on console) and looked at all the games I finished in under 20 hours at least once and enjoyed so I'll just list them here. It's in descending order from most (20.1 hours) to least (68 minutes):

I put a star next to the ones I'd recommend in a heartbeat even without the 20 hour limit.

• Mirror's Edge ★
• The Stanley Parable ★ (although may take you at least 20 to find all endings / easter eggs / secrets)
• Deus Ex: Mankind Divided ★ (due to the fact that it's the middle game in an incomplete trilogy, also recommend Deus Ex: Human Revolution but that's more than 20)
• Hotline Miami ★
• Little Inferno
• Tom Clancy's Splinter Cell
• Dishonored ★
• Myst
• DOOM (2016) ★
• Wolfenstein: The New Order ★
• Portals 1 & 2 ★
• Return of the Obra Dinn ★ (beat twice in 9 hours)
• Kentucky Route Zero ★
• The Henry Stickmin Collection ★
• FAR: Lone Sails
• Titanfall 2
• DUSK ★
• COD: Modern Warfare 2
• Ghostrunner (didn't like this but it seemed most people who weren't me did so i'm putting it here)
• Thomas Was Alone
• Jazzpunk: Director's Cut ★
• Gunpoint ★
• Orwell
• Firewatch
• Superliminal ★
• Observer_ ★
• SUPERHOT ★
• The Beginner's Guide
• BattleBlock Theater
• INSIDE ★
• EDGE
• Quadrilateral Cowboy
• Journey ★

edit: saw u said "story heavy" so i removed some of the arcadey ones. Some of these aren't exactly "story heavy" depending on ur definition but they at least have a story

Returnal, Resident Evil REmakes, most Giant Bomb games, Firewatch, Hellblade...

If you liked Alan Wake, definitely give the RE remakes and Hellblade a shot, and don't sleep on Firewatch. In fact, Hellblade: Senua's Sacrifice is probably one of the most thoughtful and atmospheric experiences in gaming (at least in the field of 3rd person, pseudo action games).

Depending on your puzzle solving abilities, Outer Wilds (not Outer Worlds!) should only take around 15-20 hours.

Extra bonus, it can be played in very short sessions very easily and has a great in-game log of events in case you have to put it down for a little while.

I'll always recommend What Remains of Edith Finch into these sorts of conversations. Absolute one of my favourite shorter experiences.

I'mma do it, I'mma be the one to bring up Undertale this time (estimated 2 hours, worth a few replays), there's also little nightmares (2-4 hours depending on platforming skills) which is a spooky little game, but not too spooky if you ever play in front of the kids.

Portal and Portal 2 must be on this list. If you’ve never played then, you must. It is that simple.

Journey is a game you could easily finish in one sitting. Short but sweet, and very easy to get swept up in the atmosphere.

Bastion or Transistor, both early Supergiant games.

Great idea for a post. I feel the same with games and novels.

I'd look at Telltale-style games. They're roughly 10 hours each ( five 2-hour ish episodes) and are almost entirely story driven. The gameplay is usually very simple. You choose dialogue choices to drive the story.

The best Telltale games are in my opinion: The Wolf Among Us, Tales from the Borderlands, The Walking Dead, Batman: The Telltale Series and its sequel, Batman: The Enemy Within. They're also releasing the first episode of The Expanse (based on the TV show since the character Camina Drummer does not exist in the books) later this month.

Another series that is very much that same style but by different devs is the Life is Strange series. I've played the first one and the prequel called Before the Storm. They are very emotionally heavy stories so I'm taking some time before I can go into the sequels but I absolutely love that series and will preach it to anyone who will listen.

10 hours is definitely short but it also helps that they are all done in 2-hour episodes so you can easily take breaks.

I haven't finished Spec Ops: The Line, but I recommend that. It looks like your average American propaganda third person shooter but the story is actually super interesting and thought provoking. Looking at https://howlongtobeat.com/, it's 6 hours for the main story.

Gris. It’s like playing an art piece.

Jade Empire - a little older Bioware action RPG, originally for the Xbox, but can be found on GOG. Runs between 12 to 20 hours.

Undertale - my favourite game of all time, easy to play, excellent story, and incredible soundtrack.

Stray.

Have you tried What Remains of Edith Finch? It's a good story heavy game that's pretty short. Return of the Obra Dinn is a deduction puzzle game that can be done in short sessions. Celeste is also good for short sessions if platformers are more of your thing.

You should give Guardians of the Galaxy a try. I’m not really a Marvel fan but the game is great and should take around 20 hours to complete.

I'm usually way more into short arcadey yet narrative games like Hotline Miami, but based on your list I'd wholeheartedly recommend What Remains of Edith Finch. It's a bunch of very short story vignettes, so even if you only have 30 minutes you know you'll complete one.

Night in the Woods might also interest you. I would always play one in-game day (which is about 1 hour each) to relax before going to bed.

If you like tactics games I recommend Wintermoor Tactics Club. Its funny and sweet and fits nicely in that time frame

• Ori and Ori: Will of the Wisps. These games are beautiful and atmospheric. The story is basic, but it's a world to get lost in.

• All of the supergiant games (except for maybe Hades). So Bastion, Transistor and Pyre. Dripping with style, Bastion and Transistor have a pretty straightforward story, but it's well told. Pyre's story is a bit more complex, with a heavy focus on characters and your choices with them.

Story-heavy: Uncharted series (between 10 and 16 hours per game), Hellblade (around 8 hours) and - if you can spare another 10 hours or so and Action RPGs are your thing - Nier Automata is really worth it (around 30 hours).
Gris was impactful enough for me that I'll mention it here, since it was super short (4 hours at most).

Undertale and Untitled Goose Game though the latter isn't very story oriented.

What Remains of Edith Finch is a beautiful game in under 2h.

A Short Hike is a wholesome short little experience, really loved it.

Journey is one of my favorite games of all time and is shorter than most movies.

Titanfall 2 campaign was 6h or something and really cool!

If you're cool with visual novels, Doki Doki Literature Club is an incredibly interesting game, not very long. It really stuck with me.

Oxenfree, A Night in the Woods, Afterparty, and Gris. Gris is a masterpiece when it comes to visuals but not story-heavy. The other three are entirely story.

Ori and the blind forest is a great platformer that is about 8-10 hours long.

Donut County is a fun little game that takes about 5 hours or less.

Axiom Verge (and 2) is a neat Metroid like game that is around 15 hrs.

I beat Myst in 19 hours of continuous game play without a guide or the internet. Best? Well, if you intend to beat it, it’ll take a lot of thinking through stories.

Checkout Somerville. It has its quirks, but I loved it overall. If you’re familiar with the game Out of This World (often referred to as Another World and vice versa), you’ll probably dig it.

Another one I recommend is Planet of Lana. Lovely little story and easy gameplay. This one really grabbed me and was an enjoyable, short playthrough.

I went through a similar period. Played a handful of easy-to-pick-up short adventure games.

Limbo and Inside are both short and atmospheric, but not story heavy at all.