: You can skip the "Preparing game data" check entirely by launching the game directly.
: Some users report that OneDrive syncing your "Documents" folder (where SC2 stores variables) can interfere with the data check. Preparing game data - Technical Support - SC2 Forums starcraft 2 preparing game data verified
Corrupted temporary files can cause the "Preparing game data" step to hang indefinitely. Preparing game data - Technical Support - SC2 Forums : You can skip the "Preparing game data"
Another common cause involves the Blizzard "Cache" and "Tools" folders. These directories store temporary files that help the launcher identify what has already been downloaded. If these files become "stale" or corrupted, the launcher may get confused, reporting that it is preparing data that it cannot actually find. In these instances, the standard fix involves manually deleting the Battle.net and Blizzard Entertainment folders located in the hidden ProgramData directory, forcing the client to rebuild the file structure from scratch. Preparing game data - Technical Support - SC2
The "Preparing Game Data" window is a known issue in StarCraft II