: pc indicates it is the Windows/Linux version (likely a Ren'Py or Unity build).
: .7z is a highly compressed archive format. You will need a program like 7-Zip or WinRAR to extract it. FutanariOfTheApocalypse-v1.0-pc.7z
: v1.0 suggests this is the first full release or a specific milestone build. : pc indicates it is the Windows/Linux version
If you are trying to verify the file or find a specific version, here is what that filename generally indicates: You might want to check the specific page
: Futanari of the Apocalypse , an adult survival/RPG indie game.
If "solid paper" refers to a password for the archive, a specific developer group, or a website source, it isn't a widely recognized one. You might want to check the specific page where you found the link (such as , Patreon , or an adult game forum) for those details.