What are some ways to create custom widgets/programs for Windows desktop?

I recently got Rainmeter, and got this widget called GameHub, which I think is really cool. While I like it, I wanted to customize it a bit for myself, and it’s a bit hard to understand how it works to change the more complicated things.

So as a CS student, I had the idea that I should try to create my own widget. Where I could click on a button on the desktop to open up a fullscreen menu of my games to be able to launch. But the problem with that is I am not sure how I could go about creating a widget like that for Windows.

I know I can use Rainmeter, but I was wondering if there’s any other way I could make this widget. Like how could I make a program that’s specifically the widget to run directly on windows instead of through Rainmeter?