Can I run Puzzle Pro 3.1 as a standalone application?
No, you cannot. Puzzle Pro 3.1 is a Photoshop plug-in. Thus, you should use Puzzle Pro 3.1 with the hosts, such as: Adobe Photoshop Elements, Adobe Image Ready, Adobe Fireworks (formerly Macromedia Fireworks), Corel Paint Shop Pro, Corel Photo-Paint, Ulead PhotoImpact, etc.). See the list of the supported hosts in the description of this Photoshop plugin.