Pretty simple, I just got off of work and wanted to play some pub matches and Steam says NS2 ins't installed outta teh blue. No other games but NS2 are having this issue, although NS2 is the only one that is installed on a separate location from the steam default. The game runs much better on SSD so I had put it on my new one that I got a short while ago.
I have ran the game from folder, and while it said it needed to optimize from an update it was working fine. Just trying to figure out how to get steam to recognize that the game is installed. Any ideas on how to do that? I could reinstall it but I'd rather see if there were a simpler fix before hand.