Just wondered if there has been a major update to Aerofly. Today when I tried to start Aerofly, steam wanted to install it and it is currently showing in my steam library as not installed. All the files in the main Aerofly folder are missing, but all the subfolders are present and have files and total about 143GB. All my other steam games are OK, I haven't uninstalled anything in steam recently and Aerofly was working fine yesterday.
No, there was no major update that I know of.
Seems like you're encountering a steam issue here, I'd search the internet on "how to rediscover steam game files".
Yep, turned out to be a steam issue. You just need to reinstall the game and then steam looks for existing installed files rather than downloading again. The only problem I encountered is that the total Aerofly install exceeded the free space on the SSD where it was installed, so Steam refused to proceed any further as it compares the game DLC with free space available. Steam isn't smart enough to check for existing files before checking for free HDD space. The solution was to turn off all DLC for the game, then try to install Aerofly again. This worked as the game then didn't exceed the free HDD space and steam reinstalled the game. I then turned on the DLC one by one and steam again found the existing files as luckily no single DLC exceeded the free HDD space. Lucky save.
I had the same problem a couple of months back and had to delete a couple of games to fake space, because all the files were actually there, it just needed to reconnect.