Cached Server Downloads
If your game updates are coming down as the "old" updates, you could have caching enabled on your servers. If this is the case, in your update string for game updates instead of using "mywebsite.com/update.exe" use "mywebsite.com/update.exe?1928388" - try not to enable caching on executable, msi or zip files. This will just cause you headaches. GLC works perfectly for game updating, you just have to know this tidbit if you find yourself in a position where old downloads are coming down. It's not a GLC issue, it's a server issue.