Hi there!
The Game is not starting under Ubuntu 14.04. It launches for a second (black screen) then quits back to desktop with the icon still active.
Starting the executables from the game-folder gives the same result (both 32 and 64 bit). The terminal output:
--------------------------------------------------------------------------------------------------------
Running Race The Sun
Set current directory to /home/andi/Spiele/Race The Sun/game
Found path: /home/andi/Spiele/Race The Sun/game/RaceTheSun.x86_64
Mono path[0] = '/home/andi/Spiele/Race The Sun/game/RaceTheSun_Data/Managed'
Mono path[1] = '/home/andi/Spiele/Race The Sun/game/RaceTheSun_Data/Mono'
Mono config path = '/home/andi/Spiele/Race The Sun/game/RaceTheSun_Data/Mono/etc'
displaymanager : xrandr version warning. 1.4
client has 4 screens
displaymanager screen (0)(DVI-I-1): 1920 x 1080
displaymanager screen (1)(HDMI-0): 1920 x 1080
Using libudev for joystick management


Importing game controller configs
Found /dev/input/event8
Microsoft X-Box 360 pad: Mapping b0.0 to b0
Microsoft X-Box 360 pad: Mapping b1.0 to b1
Microsoft X-Box 360 pad: Mapping b6.0 to b6
Microsoft X-Box 360 pad: Mapping h0.4 to a7
Microsoft X-Box 360 pad: Mapping h0.8 to a6
Microsoft X-Box 360 pad: Mapping h0.2 to a6
Microsoft X-Box 360 pad: Mapping h0.1 to a7
Microsoft X-Box 360 pad: Mapping b8.0 to b8
Microsoft X-Box 360 pad: Mapping b4.0 to b4
Microsoft X-Box 360 pad: Mapping b9.0 to b9
Microsoft X-Box 360 pad: Mapping a2.0 to a2
Microsoft X-Box 360 pad: Mapping a0.0 to a0
Microsoft X-Box 360 pad: Mapping a1.0 to a1
Microsoft X-Box 360 pad: Mapping b5.0 to b5
Microsoft X-Box 360 pad: Mapping b10.0 to b10
Microsoft X-Box 360 pad: Mapping a5.0 to a5
Microsoft X-Box 360 pad: Mapping a3.0 to a3
Microsoft X-Box 360 pad: Mapping a4.0 to a4
Microsoft X-Box 360 pad: Mapping b7.0 to b7
Microsoft X-Box 360 pad: Mapping b2.0 to b2
Microsoft X-Box 360 pad: Mapping b3.0 to b3
Assigning joystick 1
-----------------------------------------------------------------------------------------------
Does anyone know a fix to this?
Thanks!

Can you post here the contents of ~/.config/unity3d/Flippfly/RaceTheSun/Player.log ?