From what I've read, The Little Ones is a side story focuses on the children and their daily goings-on during the war depicted in This War of Mine. I don't know if it's more light-hearted than This War of Mine since I've heard that This War of Mine is pretty harsh in its depiction of what war is like.
Not harsh, accurate. The game has no problem showing you the horrors civilians go through during war. Game isn't fun, which is kinda important for a video game. It's the only game I've gotten a steam refund for.
With that said the controls should be great on a touch screen and $5 isn't terrible to satisfy your morbid curiosity