If the words need to be scrunched together, I would suggest using "camel case" for key names, e.g.
UnlockedLevel. That makes it a bit easier to read the name. I would also suggest checking for the key name in the dictionary:
unlockedlevel = data["UnlockedLevel"]
That way, the game can be programmed to react to data that isn't there. If the data isn't being saved to a file, or the file doesn't have the data, then that issue will have to be addressed.