My system specs are as follows (taken from Steam system information):

Processor Information:
    Vendor:  AuthenticAMD
    CPU Family:  0x15
    CPU Model:  0x1
    CPU Stepping:  0x2
    CPU Type:  0x0
    Speed:  3600 Mhz
    8 logical processors
    8 physical processors
    HyperThreading:  Unsupported
    FCMOV:  Supported
    SSE2:  Supported
    SSE3:  Supported
    SSSE3:  Supported
    SSE4a:  Supported
    SSE41:  Supported
    SSE42:  Supported
    
Network Information:
    Network Speed:  
    
Operating System Version:
    Ubuntu 14.04 LTS (64 bit)
    Kernel Name:  Linux
    Kernel Version:  3.15.0-031500rc2-generic
    X Server Vendor:  The X.Org Foundation
    X Server Release:  11501000
    X Window Manager:  KWin
    Steam Runtime Version:  steam-runtime-release_2014-02-05
    
Video Card:
    Driver:  X.Org Gallium 0.4 on AMD PITCAIRN

    Driver Version:  3.0 Mesa 10.2.0-devel (git-7cb3bbf trusty-oibaf-ppa)
    OpenGL Version: 3.0
    Desktop Color Depth: 24 bits per pixel
    Monitor Refresh Rate: 60 Hz
    VendorID:  0x1002
    DeviceID:  0x6818
    Number of Monitors:  1
    Number of Logical Video Cards:  1
    Primary Display Resolution:  1920 x 1080
    Desktop Resolution: 1920 x 1080
    Primary Display Size: 18,78" x 10,55"  (21,54" diag)
                                            47,7cm x 26,8cm  (54,7cm diag)
    Primary VRAM Not Detected
    
Sound card:
    Audio device: Realtek ALC889
    
Memory:
    RAM:  15865 Mb
    
Miscellaneous:
    UI Language:  English
    LANG:  es_ES.UTF-8
    Microphone:  Not set
    Total Hard Disk Space Available:  469324 Mb
    Largest Free Hard Disk Block:  35328 Mb
    
Installed software:
    
Recent Failure Reports:
    
GPU is a Radeon HD 7870, using radeonsi git 2014.04.21 (7cb3bbf) from oibaf ppa recompiled with llvm 3.5 (svn 206757).

Even after bug #60929 was fixed I have been experiencing system hangs with LITTLE Racers Street, which is based on mono. The hang usually happens randomly after a few races have been played and results in the image in the screen getting its colors corrupted (just like when in old times you changed the color depth in windows 95 -I'll try to get a picture with a camera because the system is hard locked-) and a loop in the sound. So just a hard lock.

I did not know what was to blame and was waiting for a game update in order to see if things got solved.

However, I have recently bought Foosball Street Edition (also based on mono). The game launches and shows the menus OK, but hangs the system at about 5-10 secs after the kick-off of any match. The hang is not like LITTLE Racers Street, but rather like a series of GPU hangs and recoveries (screen goes black and then shows the game a few times in a row) which end up in the system totally frozen. During that time there is no sound playing. So probably not a lock as hard as in LITTLE Racers Street.

I'm not sure how to debug this but I am quite convinced that this could be another case of mono + llvm backend incompatibility. The reason for that belief is that (i) I have tested this game on this same PC with catalyst and the game does not hang and everything works wonderfully, (ii) I obtained the same good results in a laptop with a Radeon HD 4570 (r600g, not llvm) (mesa git from around 10 April); and (iii) both games are based on mono.

As stated above, I'm not sure how to debug this because when the system hangs, it does not allow VT switching to check the logs or the dmesg output. I would be happy to help with any further information needed.

Regards