I had been using the linux steam client under kde successfully since the closed beta.
Both on Linuxmint (kde) 13 and recently Linuxmint (kde) 14
The only game I was playing was TF2.

After a recent update (about 3 days ago ?) TF2 would hang before showing the intro video.
Trying with -novid as a launch option did result in first expected loading screen but it would still hang. I also tried with the overlay disabled but while the error messages in the terminal were reduced the game still hung at the same place.

I have tried completely purging both the deb and the three steam directories in my home directory (.steam .local/share/steam & Steam) and reinstalling but the hang remains.
Out of curiosity I installed Half life. This also hangs.

I already had gnome installed (some dependancy in the list of packages I always install on a fresh OS install had dragged the whole of gnome in !) and I noticed that one of the errors in the terminal output mentioned gtk so I tried starting under gnome. It works

This is the terminal output for the starting of steam then TF2 under KDE (with overlay enabled) up until the hang.

Please ask if any more information would be of use.

me@upstairs ~ $ steam steam://open/games
Running Steam on linuxmint 14 64-bit
STEAM_RUNTIME is enabled automatically
Installing breakpad exception handler for appid(steam)/version(1360282734_client)
Installing breakpad exception handler for appid(steam)/version(1360282734_client)
unlinked 0 orphaned pipes
Installing breakpad exception handler for appid(steam)/version(1360282734_client)
[0208/171018:WARNING:proxy_service.cc(646)] PAC support disabled because there is no system implementation
Installing breakpad exception handler for appid(steam)/version(1360282734_client)
Installing breakpad exception handler for appid(steam)/version(1360282734_client)
Installing breakpad exception handler for appid(steam)/version(1360282734_client)
PulseAudio connect failed (used only for Mic Volume Control) with error: Access denied
Installing breakpad exception handler for appid(steam)/version(1360282734_client)
Generating new string page texture 2: 48x256, total string texture memory is 49.15 KB
Generating new string page texture 3: 256x256, total string texture memory is 311.30 KB
Installing breakpad exception handler for appid(steam)/version(1360282734_client)

(steam:19969): Gtk-WARNING **: Unable to locate theme engine in module_path: "oxygen-gtk",

(steam:19969): Gtk-WARNING **: Unable to locate theme engine in module_path: "oxygen-gtk",
Installing breakpad exception handler for appid(steam)/version(1360282734_client)
Installing breakpad exception handler for appid(steam)/version(1360282734_client)
Adding license for package 0
Adding license for package 1
Adding license for package 11
Adding license for package 469
Adding license for package 1187
Adding license for package 4152
Adding license for package 7353
Adding license for package 16222
Adding license for package 16549
roaming config store loaded successfully - 1255 bytes.
migrating temporary roaming config store
ExecCommandLine: "/home/me/.local/share/Steam/ubuntu12_32/steam steam://open/games"
ExecSteamURL: "steam://open/games"
`menu_proxy_module_load': /home/me/.local/share/Steam/ubuntu12_32/steam: undefined symbol: menu_proxy_module_load

(steam:19969): Gtk-WARNING **: Failed to load type module: (null)

Generating new string page texture 81: 1024x256, total string texture memory is 1.36 MB
Generating new string page texture 82: 128x256, total string texture memory is 1.49 MB                                               
Generating new string page texture 83: 128x256, total string texture memory is 131.07 KB                                             
Generating new string page texture 84: 64x256, total string texture memory is 1.56 MB                                                
Generating new string page texture 85: 8x256, total string texture memory is 1.56 MB                                                 
Generating new string page texture 86: 32x256, total string texture memory is 1.60 MB                                                
Generating new string page texture 89: 128x256, total string texture memory is 1.73 MB                                               
Generating new string page texture 90: 384x256, total string texture memory is 2.12 MB
Generating new string page texture 98: 128x256, total string texture memory is 2.25 MB
Generating new string page texture 99: 256x256, total string texture memory is 2.51 MB
Generating new string page texture 101: 16x256, total string texture memory is 2.53 MB
Installing breakpad exception handler for appid(steam)/version(1360282734_client)
System startup time: 14.97 seconds
Running Steam on linuxmint 14 64-bit
STEAM_RUNTIME has been set by the user to: /home/me/.local/share/Steam/ubuntu12_32/steam-runtime
ExecCommandLine: "/home/me/.steam/root/ubuntu12_32/steam steam://open/driverhelperready"
ExecSteamURL: "steam://open/driverhelperready"
Generating new string page texture 128: 256x256, total string texture memory is 393.22 KB
Installing breakpad exception handler for appid(steam)/version(1360282734_client)
Game update: AppID 440 "Team Fortress 2", ProcID 20088, IP 0.0.0.0:0
ERROR: ld.so: object 'gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded: ignored.
ERROR: ld.so: object 'gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded: ignored.
ERROR: ld.so: object 'gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded: ignored.
ERROR: ld.so: object 'gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded: ignored.
ERROR: ld.so: object 'gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded: ignored.
saving roaming config store to 'sharedconfig.vdf'
roaming config store 2 saved successfully
SDL video target is 'x11'
SDL video target is 'x11'
SDL failed to create GL compatibility profile (whichProfile=0!
This system supports the OpenGL extension GL_EXT_framebuffer_object.
This system supports the OpenGL extension GL_EXT_framebuffer_blit.
This system supports the OpenGL extension GL_EXT_framebuffer_multisample.
This system DOES NOT support the OpenGL extension GL_APPLE_fence.
This system supports the OpenGL extension GL_NV_fence.
This system supports the OpenGL extension GL_ARB_sync.
This system supports the OpenGL extension GL_EXT_draw_buffers2.
This system supports the OpenGL extension GL_EXT_bindable_uniform.
This system DOES NOT support the OpenGL extension GL_APPLE_flush_buffer_range.
This system supports the OpenGL extension GL_ARB_map_buffer_range.
This system supports the OpenGL extension GL_ARB_vertex_buffer_object.
This system supports the OpenGL extension GL_ARB_occlusion_query.
This system DOES NOT support the OpenGL extension GL_APPLE_texture_range.
This system DOES NOT support the OpenGL extension GL_APPLE_client_storage.
This system DOES NOT support the OpenGL extension GL_ARB_uniform_buffer.
This system supports the OpenGL extension GL_ARB_vertex_array_bgra.
This system supports the OpenGL extension GL_EXT_vertex_array_bgra.
This system supports the OpenGL extension GL_ARB_framebuffer_object.
This system DOES NOT support the OpenGL extension GL_GREMEDY_string_marker.
This system supports the OpenGL extension GL_ARB_debug_output.
This system supports the OpenGL extension GL_EXT_direct_state_access.
This system DOES NOT support the OpenGL extension GL_NV_bindless_texture.
This system DOES NOT support the OpenGL extension GL_AMD_pinned_memory.
This system supports the OpenGL extension GL_EXT_framebuffer_multisample_blit_scaled.
This system supports the OpenGL extension GL_EXT_texture_sRGB_decode.
This system supports the OpenGL extension GL_NVX_gpu_memory_info.
This system DOES NOT support the OpenGL extension GL_ATI_meminfo.
This system supports the OpenGL extension GL_EXT_texture_compression_s3tc.
This system supports the OpenGL extension GLX_EXT_swap_control_tear.
GL_NV_bindless_texture: DISABLED
GL_AMD_pinned_memory: DISABLED
GL_EXT_texture_sRGB_decode: AVAILABLE
Installing breakpad exception handler for appid(gameoverlayui)/version(20130207143422_client)
Installing breakpad exception handler for appid(gameoverlayui)/version(1.0_client)
Installing breakpad exception handler for appid(gameoverlayui)/version(1.0_client)
Installing breakpad exception handler for appid(gameoverlayui)/version(1.0_client)
[0208/171211:WARNING:proxy_service.cc(646)] PAC support disabled because there is no system implementation
Using breakpad crash handler
Setting breakpad minidump AppID = 440
Forcing breakpad minidump interfaces to load
Looking up breakpad interfaces from steamclient
Calling BreakpadMiniDumpSystemInit
Looking up breakpad interfaces from steamclient
Calling BreakpadMiniDumpSystemInit
Steam_SetMinidumpSteamID:  Caching Steam ID:  76561197970658557 [API loaded yes]
Steam_SetMinidumpSteamID:  Setting Steam ID:  76561197970658557
GL_NVX_gpu_memory_info: AVAILABLE
GL_ATI_meminfo: UNAVAILABLE
GL_NVX_gpu_memory_info: Total Dedicated: 1047872, Total Avail: 1048576, Current Avail: 872948
GL_MAX_SAMPLES_EXT: 32
[0208/171213:ERROR:resource_bundle.cc(411)] Failed to load /home/me/.local/share/Steam/SteamApps/gripped/Team Fortress 2/cef_gtk.pak
Some features may not be available.
[0208/171213:WARNING:proxy_service.cc(646)] PAC support disabled because there is no system implementation
CShaderDeviceMgrBase::GetRecommendedConfigurationInfo: CPU speed: 2800 MHz, Processor: AuthenticAMD
GlobalMemoryStatus: 4294967295
CShaderDeviceMgrBase::GetRecommendedConfigurationInfo: CPU speed: 2800 MHz, Processor: AuthenticAMD
GlobalMemoryStatus: 4294967295
IDirect3DDevice9::Create: BackBufWidth: 1600, BackBufHeight: 900, D3DFMT: 3, BackBufCount: 1, MultisampleType: 0, MultisampleQuality: 0
ERROR: ld.so: object 'gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded: ignored.
ERROR: ld.so: object 'gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded: ignored.