What are you talking about?

Ok, lets roll back a little, before talking about "playing in PDFs", let's talk about PDFs.
As it turns out PDFs do a lot and sometime  too little.

When PDFs don't work!

Most tabletop RPGs are available as PDF, yay!
I say most, because sometime the physicality of the experience cannot be replicated in a digital format.
Case in point with A Handful of Grubblings from Evlyn Moreau, where the furry, googly eyed, hand stitched, riso printed zine is something to experience.

So not every RPG needs a PDF and that's OK.
Since most of them do, so lets talk about what kind PDFs are there.

What are PDFs for?

Not PDFs are created equal, because the people using them needs different things.
A commercial printer will need all layers flatten, margin with guides where the paper will cut and a subtractive color model like CMYK.
People printing at home vary, so some want the full colour print, but other would rather have a black and white version.
The printing, commercial or home scale, is probably not the biggest use of a PDF.

People that print PDFs will likely print it only once (if they print it at all that is), but people reading that PDF will read it a lot.
And their need is a lot different: the text to be searchable,  selectable (I read a lot by selecting/highliting sentences), they need copy paste the text elsewhere, they need a screen reader to vocalise the text and images. The PDF is used a lot more like website than book.

PDFs as App

I've experience beautiful design on the web on my mobile phone over the years, less so with PDFs.
James Chip provided a tool to use ePub as ePub might well bridge that gap between PDFS and HTML , proof that there is a lot of discontent with PDFs  when used digitally.

There is also a lot of (web) apps to play or help play a game.
Some replacing the need for the books altogether (I won't name it, but you know the one).
Others, providing the middle ground between the rules in the PDF and the playing experience, like the excelent Stargazer by Nick Boughton
So there is clearly a gap between what PDFs provide and what people need to play.

Playing in PDFs

Turns out, there is a lot that can be done with PDFs, even if Adobe monopoly on the "portable document format" has not helped people to use the power feature of the format.
PDFs can have fields, drop down, tick box etc. and we use those feature in Notorious Style's PDF for the character sheet, location sheet and NPC sheet.
Provided you use a PDFs app that allow you to  with editable PDFs (Xodo, the default google drive PDF app, the default app on apple thing, etc), you could record everything in the PDF, save it  and continue playing where you left when you open it again.
The only bit we have not figured out yet, is how to make a random dice roller in the PDF so that there is no need to switch to a dice app.
If you know how to do that, please send us some tips in the comment.