From PsyHelp

• Is a standard Add-on.

How to get it

• "Study" a Library Blueprint with the required materials

Uses

• Reduces maximum house size by 100 in return for unlimited space to store books. (Note that you can ONLY add books to the library, other print items are excldued)
• Stores books like the Basement - including removing comments.
• A random book in your library will have the action 'pull' which opens up a batcave where you can buy the Bat Costume and trade in five Basement Blueprints for one additional unit of Basement space (or 500 blueprints for a new level).

Notes

• For the location in "The City," see The Library