Kids is a non-traditional game. It has very few game mechanics to even discuss.
I would describe it as more of a experience than a game. The game is more about observing what happens than controlling it. Your controls are very limited, and you have very little input. If you are considering getting a new game purely for fun and enjoyment, then I do not recommend this. However, there is great value in this game. It is well worth the $3 asking price.
The true value of this game is its message and the imagery. The game clearly is conveying a message relating to peer pressure and group interaction. A lot of the game is getting all of the people to agree to do something or another. There are moments in the game where people are cast out because of their disagreement. Eventually they all succumb to joining the masses. To me, the message is clearly that kids need to be able to make more individual choices in life, in that those who invariably follow the group suffer a terrible fate.
The Extremely short version if you want to know whether to play it or not: If you are looking for game play, then do not play this. If you are looking for a visual experience, similar to a video, then this is the game for you.
To sum up the message: Peer pressure is common and you need to practice thinking for yourself. This game provides you with that opportunity.
Little Nightmares is a 3rd person 3D side-scrolling horror puzzle game.
The game-play is mostly puzzle solving with some elements of stealth that you might find quite similar to FNAF Security Breach. It lasts for about 7-12 hours in that it is quite variable. The world in the game is very well made and defined. You could easily spend hours just exploring the art and 3D generated environment. Unlike traditional horror games, this does not have many jump-scares. It is atmospheric horror that is shown well with the lighting and general area.
The message in the game is not very clear, in that there is a massive expanse of imagery and conflicting themes. Before you continue reading, there are spoilers ahead in this paragraph, so skip this one if you don't want them. You wake up after seeing a strange dream. The first part of the game is walking around a place that looks similar if you crossed a prison with a nursery. The main other creature that inhabits the area is the Janitor. It has two very long arms, a very large head wrapped in bandages, and very short and small legs. It seems to patrol this area to keep things under control and make sure the children from the nursery don't escape.