Amnesia: The Dark Descent - Remastered on Linux
This is a fan made mod for Amnesia: The Dark Descent, that the final version recently came out on ModDB. It's even approved by the devs (who later open-sourced the engine behind the game, making a lot of stuff possible for a 10 year old game).
The mod not just makes the game look better and sound better, but there are some really nice additions to the map. Which means unfortunately that your former saves won't work with this version. Check out the detailed changes on the above link!
All in all, it's worth a try, especially if you have some beefy machine. Not gonna lie, the load times are increased significantly, but I don't care, because so far I didn't have crashes and other problems, and the game seems to play just fine.
Remastered version on Linux
Luckily it's very easy to install. It's a .rar file, which means we need unrar or other utility. Extract to somewhere safe, don't do it directly to the game directory just yet.
After that, you will get an "Amnesia Dark Descent - Remastered" directory, where you will have file called mainsettings.cfg and the directory with game mod.
First copy the "mainsettings.cfg" into your HOME directory, where you can find a .frictionalgames/Amnesia/Main directory. This is basically where your game settings and saves are. Also make a backup of this file, so if you experience some problems you can revert it. If you want to be extra safe, just backup the .frictionalgames directory.
Second, copy the content of "Amnesia The Dark Descent" to your Amnesia/game directory, that's inside the game directory. If it gives you the prompt to overwrite, then it's good!
Then just start the game. It will give you the first start texts, plus a new menu background. When you start a game you will have a new side room in the starting area.