Tried checking the game file's integrity ?

Solution is to... click again and it will start :)

well it didnt launch but I changed steam skin and it magically launched

i had the same problem and deinstalled ZoneAlarm Firewall-service. if you have Zone Alarm installed, a deinstall could help.

watch this; http://forums.bistudio.com/showthread.php?147513-Uninstall-ZoneAlarm-if-Alpha-not-starting&p=2314798&viewfull=1#post2314798

ah got it working, just changed steam skin:P thank you all

I get a similar behavior but after several attempts game does launch.

Furthermore, every fail leaves an instance of steam.exe running with one thread suspended on CreateInterface+0x5697c.
It uses less than a megabyte of memory. Parent process appears to be Arma, but it dies very quickly and I cannot confirm that.
Command line:
"D:\Program Files (x86)\Steam\steam.exe" -applaunch 107410
Current directory:
D:\Program Files (x86)\Steam\steamapps\common\Arma 3\

Strangely, attempting to inspect the stack with Process Explorer gets it unstuck and game gets launched. Here is the reported stack: http://i.imgur.com/SGmbJlP.png

Another steam skin issue. Closing