Plotypus isn't available in stores but you can print your own copy. The content is under a Creative Commons license that allows for free use and remixing, with a few caveats.

The PDF is formatted for Print & Play Productions - an easy, inexpensive way to prototype games. Use standard size cards (2.5" x 3.5"), gloss stock, double sided, with the PDF uploaded as the Front (ignore the Back upload). You can also use their standard tuckbox to store the game - I have custom box art below.

Deck formatted for Print & Play Productions: Plotypus Deck PDF
Box art for Print & Play tuck box: Box Art PDF

If you're printing at home - it might be helpful to use a copy of the PDF with the card borders. Definitely do not use this with Print & Play Productions.

If you want to include an abridged manual, you can use this file. It's formated to be double-sided and cut down to more easily fit in the box.