You can download software for RISC OS from the two app stores !Store and !Packman that are usually part of the RISC OS distribution. But here is a list of websites where you can get RISC OS software also.
Free software
Games and emulators
JASPP – Acorn Software Preservation Project
https://forums.jaspp.org.uk/forum/index.php
Nemo’s RISC OS page / Tools
Video and Tools
Rick Murray’s RISC OS page
https://heyrick.eu/blog/index.php?diary=20201227
Games and emulators
Games and emulators