I wonder what's the minimum that is gaming capable
For the absolute minimum I would turn to Linux.
Steam is available for Linux and shows over 26000 games that are available.
A lightweight Linux distro running only processes needed for gaming would probably be the answer.
Judging from the results on
www.reddit.com
200-300 megabytes sounds reasonable for the Linux OS itself.
Depending on the game you intend on running the actual amount of ram needed can vary wildly.
Cities:Skylines took about 2 gigabytes to load the home screen.
My simplest and least ram intensive Linux compatible game is Factorio clocking in at 350 megabytes of ram.
Cooking clicker while not Linux compatible only uses 184 megabytes of ram
(Those ram figures were taken from Windows 11 ... probably similar on Linux)
This would give us a minimum of 384-650 megabytes of ram to avoid using virtual memory on a linux/properly slimmed down Windows install.