You give no measurements of the space. Maybe this houzz article can give you some ideas.

https://www.houzz.com/magazine/8-clever-ideas-for-the-space-under-the-stairs-stsetivw-vs~52888847

Before we create something you don't' need in this wacky space, do you need a simple closet to hold luggage or storage for something else? Otherwise we're just creating a vignette you'll have to dust.

Canvas is mounted on free standing easel.

Thanks for the comments! The far right wall is 38”, the wall in the centre is 34” and the angled wall is also approx 38”.

The reason for the weird wall angle is that there is a post on the far right wall that we boxed in during construction. We would need to be able to remove whatever is in there so we can bring things down to the basement and have that wiggle room

Not sure why they left it there, being that it's a basement, unless you're gonna put a table with a few pictures or some statue, I would just put a wall there with a door and make extra storage IMO, it will be a much more useful space.

Nothing on the floor.

On the walls, this is the perfect spot to do a gallery with family photos or kids' works of art.

I agree on using the space as an art gallery. Maybe 3 long paintings (one on each wall segment) that are hung at the same height.

My daughter and SIL's home has a similar odd space in their 2nd story kids hang out/T.V. room. Bedrooms are off on either side of the room. They have placed a study desk and chair in the odd space for their teen to sit down and get his homework done.

The space of the space is unattractive and adding art just brings your attention to the space. Use it for storage and hang a curtain to cover it up. You can take it down when needed for moving items through this tight passage. Even if you don't need storage, I'd hang a curtain anyway and just make the space disappear.

You could make it into a small reading nook or just a small entry way for the basement area. The images below are from a few of our designs for our clients. Please take a note of the tables and chairs in both images. You could also add a floor lamp, small rug, and artwork to the space.

Parisian Elegance · More Info

Traditional Renovation · More Info

It made me think of what they called ’coffin corners’ in old homes. Except yours is downstairs instead of upstairs! . Revisited Myth # 58: Niches called ‘coffin corners’ were built into staircases to allow people to carry a casket downstairs and turn the corner.