This fits your price requirement and is a nice chill game to just lose yourself in and perfect for the deck IMO.

A Short Hike. Currently €6.59 in Europe.

Hope things improve for you soon.

The Dishonored series is amazing and is usually pretty cheap when on sale. A couple bucks at most, maybe.

Another immersive sim to recommend would be Prey. The DLC is really good too

If you want a big open world game, I can recommend Mad Max, you can find it in fanatical (a legal and trusted store) for $2.49. I had a lot of fun with it and it will give you tons of hours of fun.

https://www.fanatical.com/en/game/mad-max

I actually recommend you that site for steam keys since they often do bundles very cheap to help your library grow without spending a fortune.

Absolutely try Prey from 2017, it is an immersive sim that is now looked at as a modern cult-classic. You wont be disappointed.

Just wait for a sale if $30 is too high, it goes on sale regularly.

Yakuza zero has been great on the steam deck for me. I think it kinda straddles the line between immersive sim while mostly being a brawler.

I would strongly recommend Disco Elysium, which is a very unique RPG with excellent writing.

https://store.steampowered.com/app/632470/Disco_Elysium__The_Final_Cut/

Batman Arkham series runs well.

Maybe kotor? Knights of the old republic.

"Mark of the ninja" low sysreq sidescrolling stealth game, multiple routes/playstyles. lots of fun, should be cheap too

both very elegant and gameplay-first, but also oldschool-cool:

chained echoes

it's absolutely lovely on the steam deck because the readability and contrasts are good even in sunlit environment, and the battery life will be good

I've really been enjoying Kingdom Come: Deliverance and swapping between my PC and SteamDeck. It runs pretty well on the Deck. Reminds me of how I felt playing Skyrim. Excited to get to the sequel.

Have you played the BioShock series?

valheim and skyrim

i am a much more relaxed gamer on the deck and oh boy these games have such a satisfying layer to them when just vibing there. spent an hour hiking the mistlands for the vibe last week

valheim is a bit more on the expensive side but skyrim is often for sale at like 10 bux

NieR:Automata and NieR:Replicant run great in the deck

Cocoon

Based on the games you listed, Morrowind! One of my absolute favorite old RPGs. Out of the elder scrolls games it's the one with the strongest world building, which paints a nuanced picture of a very strange and compelling world. Compared to Skyrim in particular it's more like a pen-and-paper rpg and less like an action game which gives it a higher barrier to entry. In particular, a lot of people find the combat frustrating at the start.

The modding community for the game is very active to this day. To begin with, there's OpenMW which is a re-implementation of the engine that runs natively on Linux and contains various bug fixes and quality of life features. There's also a fork of it, tes3mp, which allows you to play Morrowind in multiplayer!

There's also Tamriel Rebuilt which is a modding project that adds the mainland of Morrowind (the base game just takes place on an island called Vvardenfell) and adds maybe another game worth of content. Theres also Project Tamriel which has one project that recreates Skyrim based on Morrowind-era lore and one that recreates Cyrodiil based on Morrowind-era lore.

I had the most fun with Vampire Survivors - addictive, relatively short bursts, but suitable for longer sessions. Dirt cheap.

I also liked MultiVersus.... before it became a micro-transaction filled abomination. The core gameplay loop is still great tho.

General recommendation: Pick single player games from 3-4 years ago and back. The ones you were really interested in when they came out, but did not yet get around to playing them. Due to their age, they are almost guaranteed to run well on Deck, and they provide hours upon hours of fun. That's my strategy at least :)

Dark and Darker is free and is basically if Oblivion, Dark Souls and Escape from Tarkov had a baby.

Shadows of doubt feels similar to old school Deus Ex. $30 normal price, so wait for a sale.

You run around a dark rainy city as an ex cop turned freelance detective.

Take up small side jobs, break into buildings, make phone calls, buy coffee, listen to jazz in your apartment, read about a murder in the paper, sneak into a bloody crime scene to gather clues, hack computers, make a tangled conspiracy board, drink stolen alcohol until you're staggering down alleys, have crazed monologues, get an epiphany, track down a suspect, accuse them of murder, arrest them, close the case, find out they were innocent after all, repeat

Dave the Diver was fantastic and is perfect for the Deck.

Some other games I liked playing this year on the Deck:

Chained Echoes

Vampire Survivors

Eastward

Divinity Original Sin 2

Slay the spire

Balatro

Chrono Trigger

Stardew Valley

Inscryption (mouse and keyboard required)

Edit: I got them all below or around $10, but some of them are curently above.

Have you tried Deus Ex Randomizer? We have an unusually high number of Steam Deck players

https://mods4ever.com/project/DXRando

Kingdoms of Amalur Re-Reckoning $9.99

Hollow Knight has not been mentioned

Caves of Qud is really good, but I don't know if it is fully compatible with the Steam Deck. Very good RPG though.

Humble choice is a great way to discover gems https://www.humblebundle.com/membership

Monster hunter world and monster hunter rise run great on the deck

Cyberpunk also runs well enough on the deck

For the price sensitive gamer: https://isthereanydeal.com/

If you like the settlement building in Fallout 4, Humble Bundle's got House Flipper 1+DLC on sale for five bucks.

House Flipper and Friends Bundle

Balatro