Shelving across the back slanting wall for the toys, and a soft washable rug on the floor will create a cozy play area. I would move the table and chairs much closer to where you shot the photo. I would only use lighting that the children cannot reach themselves, to prevent injury. The wall on the right could hold artwork created by the children.
Carolyn Albert-Kincl, ASID

I have the necessary electricity, maybe a led lighting would work somehow?

A track light, mounted on the right hand wall at 7' above floor could work. Or a couple of wall sconces of the warehouse variety, shown below. They also come in colors which could be cool in a kids' space.

I loved the idea of track light mounted on the wall . Thank you very much :)

You are most welcome, Noa! Your kids are fortunate that you want to create a special play area for them.

add tiny white lights or decorative string of light to make it fun. even some paper lanterns with those battery operated LED lights inside.