Então meu Steam acabou de morrer ontem. Então, depois que não consegui encontrar o que estava faltando, fiz uma limpeza e, em seguida, reinstalei.
miguel@miguel-ThinkPad-X230:~$ steam
Running Steam on ubuntu 16.04 64-bit
STEAM_RUNTIME is enabled automatically
[2016-09-19 19:01:27] Startup - updater built Aug 23 2016 18:24:59
Looks like steam didn't shutdown cleanly, scheduling immediate update check
[2016-09-19 19:01:27] Checking for update on startup
[2016-09-19 19:01:27] Checking for available updates...
[2016-09-19 19:01:27] Download skipped: /client/steam_client_ubuntu12 version 1471977975, installed version 1471977975
[2016-09-19 19:01:27] Nothing to do
[2016-09-19 19:01:27] Verifying installation...
[2016-09-19 19:01:27] Performing checksum verification of executable files
[2016-09-19 19:01:28] Verification complete
Refresh rate: 1
Refresh rate: 1
Refresh rate: 1
Refresh rate: 1
Refresh rate: 1
Refresh rate: 1
Refresh rate: 1
Refresh rate: 1
Refresh rate: 1
Refresh rate: 1
miguel@miguel-ThinkPad-X230:~$
Então, sim ... eu não sei o que está acontecendo. Estou executando o Ubuntu 16.04 usando um core-i5.