Other Game crashes on opening

Hello,
Dec 15 is the latest patch available, you should be good on that front. Have you tried anything so far, maybe a system restart?
You could also try reinstalling, or trying one of the mirror downloads if you think your download may be corrupt.
Without more information, it's difficult to pinpoint what it may be. Could you please navigate to the MapleLegendsHD folder and provide the most recent log from the Crash Logs folder? (You can right click the client and choose "Open file location" if you're unsure of the path to the folder.)