If you're on macOS and want to test if the 64-bit version of PiB works on your system, then please try out the beta version. Here's Valve telling you how to do that: "Right-click on the game in the Steam client and select Properties. From the Properties window, click the Betas tab." Then select "testmac64bit" from there.

• 150 paintings to solve!
  
• 15 rooms to unlock.
  
• 20 achievements.
  
• Logic puzzles similar to picross, sudoku, nonograms, paint by numbers and griddlers.
  
• Endless "Mystery Masterpiece" challenge mode.
  
• Play paintings in Normal, Pro and Master difficulty modes.
  
• Undo and redo buttons.
  
• 6 player profiles on one computer (the whole family/commune/coven can play!)
  
• Steam cloud and achievements.
  
• Play with mouse, keyboard or game controller. Also great on touchscreen PCs!
  
• Hours of puzzley fun!

• OS: Ubuntu 12.04 32/64-bit or Ubuntu 12.10 32/64-bit
• Processor: 1GHz processorMemory: 1 GB RAM
• Memory: 1 GB RAM
• Graphics: OpenGL 2.0 compatible video card with 256 MB shared or dedicated RAM (ATI or NVIDIA)
• Storage: 225 MB available space

• OS: Ubuntu 12.04 32/64-bit or Ubuntu 12.10 32/64-bit
• Processor: 2GHz processorMemory: 2 GB RAM
• Memory: 2 GB RAM
• Graphics: OpenGL 2.0 compatible video card with 256 MB shared or dedicated RAM (ATI or NVIDIA)
• Storage: 225 MB available space