So I know less than nothing about art but I feel compelled to comment anyway.
I really like Castle, Untitled, Untitled 2, Beach, City, Night Sky, Mars and Street Corner. I’ve don’t care much for hanging stuff on a wall in a house but, if I had a place of my own, I’d display these.
The cliff, hazy sky and water in Castle are great. I love that type of atmosphere and locations and the picture seems to capture that while keeping everything really simple. I don’t care much for the little castle on the left though.
No idea what Untitled is supposed to be but it looks nice. 
I don’t know what Untitled 2 is supposed to be either but it reminds me of small stones you’d find near a river.
Beach is similar to Castle and I like it for the same reasons. But just like not wanting the castle in Castle, I would like Beach a lot more if it didn’t have that bottle. Not only does it seem out of place, it reminds me of how polluted the beaches are.
Night Sky is great and unlike the bottle and castle, I don’t mind the cat.
Mars is kind of cool I guess.
Street Corner looks nice. I like the grays. It also looks like something I might be able to draw it if I tried (looks like it but if I tried, I’d fail).
I’m neutral about Warning. I like the hand shadow wolf and the sense of urgency in the stick figure as he runs away from the wolf.
Your favorite, Tree at Night isn’t bad. I would have liked it if the tree didn’t have the red in it. What’s that red supposed to be anyway?
Shark, Terrier, Bird, Bear and Monkeys just seem like a super simple animal drawing on a solid background. Kind of boring.
Don’t get the point of Game.
I think I would have liked Points if the points went all the way through the picture.
And again, I don’t know shit about art but these are pretty cool. 
Oh, I only looked at the first page.