The game files are installed, but the Steam client or dedicated launcher hasn't recognized them properly.
Aggressive security software frequently flags the game’s core executable file ( AXA.exe ) or its global asset folder ( ATC4_g ) as a false positive, completely deleting or locking it away from Steam.
How to Fix the "Application Not Found" Error in I am an Air Traffic Controller 4 i am an air traffic controller 4 application not found top
I Am an Air Traffic Controller 4 Application Not Found: Troubleshooting and Solutions
Return to the main page and navigate to →right arrow Manage settings . The game files are installed, but the Steam
ATC4 is known to conflict with cloud storage services like that sync the Documents folder. If OneDrive is actively "protecting" your Documents, the game may not be able to find its own data. Right-click the OneDrive icon in your system tray. Go to Settings > Sync and backup > Manage backup .
Starts easy but becomes frantic and challenging in later stages. ATC4 is known to conflict with cloud storage
Open your layout view and click on your main Library header tab.
Antivirus software can sometimes mistake AXA.exe , the game's main executable, for a threat. This is particularly common with AXA.exe .