It's a known issue in x86_64 Linux. If you played with i386 Linux, archievements work well.
To start Nihilumbra.x86, launch steam with setarch command:
$ setarch i386 -3 steam
NOTICE:
Seems like saved games for x86_64 are separated from x86. If you played games under x86_64 Linux before, you have to unlock all achievements again.
I copied my save over and everything that I should have earned unlocked immediately. Also, a game-specific alternative way to run the 32 bit version is to use this as the startup command in the game's preferences:
(same here)
To start Nihilumbra.x86, launch steam with setarch command:
NOTICE:
Seems like saved games for x86_64 are separated from x86. If you played games under x86_64 Linux before, you have to unlock all achievements again.
I copied my save over and everything that I should have earned unlocked immediately. Also, a game-specific alternative way to run the 32 bit version is to use this as the startup command in the game's preferences: