What is Reddit's opinion of Forward Chess?

From 3.5 billion Reddit comments

Forward Chess is great for learning openings. I've bought a few books from Quality Chess from there, and the book is combined with a board and engine at the same time! I'm learning top notch opening theory while I'm on the toilet or about to go to sleep, and can explore side lines that interest me with a computer immediately.

>How do you interact with it when you don't have PGN of the book

You can just freely move the pieces on the side board; pretty much the same as "paper book + real board" but on screen... and even if it doesn't record the moves you make, you can quickly go back to a previous position, so if you shuffled the pieces around to try a variation (either in the book, or something you wanted to look up yourself) you can revert to the mainline with a few clicks.

Actually, I rarely load the PGN even if I have it, because manually moving the pieces while you are following the game is somewhat more engaging to me, and i focus more on the content (you avoid the urge to go "right arrow, right arrow, right arrow", so to speak)

>More general questions are how many books are there that are not available in PGN format

This is a slighly trickier question... books that are available in proper digital format, are for the most part either already made interactive (i.e. Forward Chess, New in Chess, and other similar apps with custom formats) or come with PGN/other common db format (i.e. Everyman Chess, maybe some other publisher).

So, aside for some plain eBook titles for the Kindle and such, what's left out is the bulk of not actually converted books that have, well, "unofficial" scans lying around, which may or may not come with a PGN... and the above app, even if it clearly doesn't state it out loud, is mainly for making those kind of titles more accessible

You could get a book for the Forward Chess app... for example, "Chess Duels: My Games with the World Champions" is 9.99, and you can never go wrong with Yasser; for a little more there's "Tal vs Botvinnik 1960", another classic