Free Demo here - https://jonathanmcc.itch.io/dragons-lunch-demo
This is my Roguelike game written using monogame that I released to Steam in 2017.
I got lots of valuable assistance from browsing the monogame community posts.
The game uses dynamic shadows (like in a turn based roguelike) and I could never get it to work the way I wanted until I had a real go at it over the last month or two (hence my comment about assistance above).
I was drawing the background, then drawing a big black square with the triangles that make up the area visible to the player cut out of it, and then drawing all the lights.
It turns out the 2nd and 3rd steps were in the wrong order so I switched them and this improved things massively.
Take a look at the free demo if you want to see it in action.