This looks like a Steam issue but you might want to report it to the SS3 devs also.
I reported it to SS3 devs as well.
Hello @Jenco420, are you still experiencing this issue on an up to date system?
Closing pending feedback.
steamclient.dllx1 2014-09
I have been trying to get SS3 to start. keep coming back to this error
I am using 7750 HD 1g ati non free drivers and i have portal 2, Fez and Starbound working
jenco@debian:~/.local/share/Steam/SteamApps/common/Serious Sam 3/Bin$ ./Sam3
WRN: CPU Power saving is enabled and performance governor is not used.
INF: GameEnv API: Steam
dlopen failed trying to load:
/home/jenco/.local/share/Steam/ubuntu12_32/steamclient.sowith error:
libtier0_s.so: cannot open shared object file: No such file or directory
[S_API FAIL] SteamAPI_Init() failed; Sys_LoadModule failed to load: /home/jenco/.local/share/Steam/ubuntu12_32/steamclient.so
[S_API FAIL] SteamAPI_Init() failed; unable to locate a running instance of Steam, or a local steamclient.dll.
jenco@debian:~/.local/share/Steam/SteamApps/common/Serious Sam 3/Bin$