Large files missing after update, but their space is still used up

I did the latest update today. Afterwards, I noticed that a very large game, Elder Scrolls Online, was missing from the game client (Steam). However, the space it takes up (c. 80 gig on my 120 gig MacBook Air) is still taken up. When I search for it, I find the launcher; however, the launcher only asks me to install it. I also find the folder. However, the folder is only 100MB, the kind of skeleton games leave behind after you delete them. How do I figure out what's going on? I'd honestly be glad to either find the game or free up the space.