The Story of My Life and Dungeon Quest (both getting delisted from Steam, likely in ~1 week) can be played without Steam. No tricks needed.

Store links:
[The Story of My Life] https://store.steampowered.com/app/917610/The_Story_of_My_Life/
[Dungeon Quest] https://store.steampowered.com/app/849920/Dungeon_Quest/

Both are only published for Windows, but The Story of My Life also comes with a file called TheStoryofMyLife.sh that can be used as an executable on Linux (also runs without Steam).

Downloaded the games through Steam on Ubuntu 20.04, did a first time setup using Proton, then tested The Story of My Life in both an Ubuntu 20.04 and Windows 10 virtual machines, and Dungeon Quest in a Windows 10 virtual machine.

Anyone managed to get Phoenotopia: Awakening working on Windows 10?

Just running the exe says it's a "Steam link" and prompts to open it with a compatible program.
Running it with the steam_appid.txt file does start the game, but it's all borked in-game and Unity seems to panic about missing Steamworks in the log file.
Without steam_api.dll, the game closes as soon as it starts.
And with the -nosteam argument through cmd, nothing changes.

Okay, we're all updated again.

Mutiny!! (+18 game) can be played without Steam. No tricks needed. The uncensor patch can also be used outside of Steam.

Store link: https://store.steampowered.com/app/669050/Mutiny/

The game is available for Windows, macOS and Linux.

I downloaded the Linux version, but as pretty much all Ren'Py games, the Linux version also comes with a Windows executable, and vice-versa. Both the the Linux and Windows executables worked in virtual machines that never had Steam installed. Also did a first time setup beforehand.

Also, a tip:
if you can't find how to run files with special symbols from Linux's terminal, you may need to rename a few files to remove the "!!" (without quotation marks).
These files are:
~/Mutiny!!/Mutiny!!.sh
~/Mutiny!!/Mutiny!!.py
~/Mutiny!!/lib/linux-i686/Mutiny!! (if you're in a x32 distro)
~/Mutiny!!/lib/linux-x86_64/Mutiny!! (if you're in a x64 distro))

Learn Japanese To Survive! Kanji Combat can be played without Steam by either launching the executable (Windows-specific method) or launching a HTML file (seems to work on pretty much any OS). No tricks needed.

The Windows executable is the KanjiCombat.exe file in the directory ~/Learn Japanese To Survive! Kanji Combat
The file that lets you launch the game on pretty much any OS is the index.html in the directory ~/Learn Japanese To Survive! Kanji Combat/www

Store link: https://store.steampowered.com/app/759440/Learn_Japanese_To_Survive_Kanji_Combat/

Tested the Windows executable on a Windows 10 virtual machine that never had Steam installed.
Tested the HTML file in my main Linux install (has Steam installed), both virtual machines I have (Ubuntu 20.04 & Windows 10, neither ever had Steam installed) and in my Android phone (this last one is weird to make the game run, but it's possible).

Also, just like in Hiragana Battle, if you use Firefox, you need to toggle a setting in it for the game to work. For that, put about:config in the link field and open it, search for "privacy.file_unique_origin" and set it to "false".

##############################################################################################

Sougetsu Ninja: Kikyou (+18 game, getting delisted in a few days) works without Steam, no tricks needed.

Tested in a Windows 10 virtual machine that never had Steam installed, as well as in my main Linux install using Wine with its default folder instead of Proton's.

A word of warning and an advice:
The devs are removing the game because apparently a recent Windows update breaks the game and they don't know how to fix it (probably my virtual machine's Windows didn't update yet, thus it still works). If the game no longer runs to someone, there could be a few workarounds, like using Wine, virtual machines with either older Windows 10 builds or Windows 7, and downgrading your Windows' build version.

Store page: https://store.steampowered.com/app/1091040/Sougetsu_Ninja_Kikyou/

Nubarron - The Adventure of an unlucky Gnome runs fine without the client out of the box.

The game is also currently free on Steam.

Get it here: store.steampowered.com/app/414160/Nubarron_The_adventure_of_an_unlucky_gnome/

Hey is resident evil 7 drm free? Just curious :)