I have a system that runs a full-screen program (based on love2d) for long periods of time. I would like to be able to put the monitor into power-saving mode after a certain period of inactivity. Normally, I would expect windows to do this for me, but as long as this program is running, it won't. As far as I can tell the program doesn't set any requests related to power saving the way, say, VLC does - powercfg -requests and powercfg -requestsoverride shows nothing under DISPLAY. The implication is that windows itself won't turn off the monitor if a fullscreen program is running.
There's lots of literature on how to do this by changing the delay before the display powers off to something very short, but since windows won't power off the display of its own accord this doesn't help. Another answer suggested nircmd, but this just exits without doing anything; when run as a normal user it exits with code 216, and when run as administrator it exits with code 0, but in either case nothing happens.
I'm fine with writing a small C or C# program to accomplish this, although ideally I'd like to do it with existing tools.
