Hey RedDragon369,
Thanks for contributing to the Apple Support Communities.
It seems like Lego Batman 3 isn't downloading or updating properly from the App Store, but you can see the app in Launchpad.
Try the following method to restart the download:
Follow these steps while you are logged in with an administrator account:
- Enter Launchpad.
- Click and hold on an icon until you see all icons jiggle.
- Click the "x" button in the upper-left of the Mac App Store app icon you want to delete.
Note: If you do not see an "x" button, either the app is not from the Mac App Store or you are logged in as a standard user.
- Click "Delete" in the confirmation dialog to delete the app.
(From OS X Lion: How to remove Mac App Store apps that appear in Launchpad. The advice works for OS X Yosemite as well.)
- Quit App Store.
- Wait 10 seconds or more.
- Open App Store again.
(From Mac App Store: "An unknown error occurred (100)" when purchasing - Apple Support)
...click the Purchases icon, then click on the "Install" button for the app.
(From OS X Lion: How to remove Mac App Store apps that appear in Launchpad)
All the best.