Well, I've got a lot of pleasure from reading this book. It's short and funny, full of cute illustrations, that sometimes put a little smile on your face. If you are a gamer with a huge experience (like me) you definitely already know the majority of things, that "Level up!" explains to a reader like what genres of games are exist, how enemies should behave, what camera type should you use, etc. However "Level up!" is not an overview of game types and game parts, it is like a manual, full of useful adviсes, and helpful ideas if you get stuck while developing your own game. There are some lists of features that you can add (like possible environments for your level), examples of documents and presentation that you need to show to a publisher or to make development easier for your team. So, if you are keen on game development, want to know how people create the games or even want to get new ideas for your own game, this book is definitely for you. Here are some ideas, that I learned from "Level up!", you can read it as well and decide if this book is worth reading for you.
The first thought from the book, that I considered very useful is that if you want to generate new interesting ideas, you should do things, that you are not doing in your casual life. You should read books about things that you never thought before (like gardening for me, or history of Bhutan, or even tutorial for plumbers) to expand your purview and get ideas from different fields. You should be curious and always learn something new to get interesting ideas.
If you stuck and cannot get any idea from your head, you should take a break. It is a very simple point, but not very obvious. Even my experience shows that breaks work well for your mind. Sports even better. When you sit all day blood doesn't circulate in your veins actively and your brain doesn't get a proper amount of oxygen. Let's jog!!
One more idea is about children. When you make a game for children, be sure that children want to look older, than they are. You should sell a game for 13 years old children to 10 years old children, for 15 years old to 13 years old etc. The worst thing that you can hear from a child about your game is "This game is for my little brother!"
Next thought is about story in a game. Gameplay is meat and story is salt. You need an exact amount of story to make a game feel tasty. Plot twist should occur every 15 minutes, you also need to have a start, middle and the ending of the story. There are a lot of scripting twists, to make your story feel more exciting but I guess it is a theme for another book. There is the triangle of weirdness (which consists of characters, activities, and the world) and you should have only one weird thing from three. If you have more than one, player would be confused and frustrated and will turn your game off.
Game design is about creating an experience for players. I was really amazed when I've read about Left for Dead AI. It measures the stress level of the player (it depends on various parameters, like a current health of the player, his skill, his behavior etc.) and controls the enemies spawn speed, ammo spawn speed, difficulty and even music to make your experience more exciting!
Paperwork is what you need in any job. As a game designer, you need to provide the full vision of your game to all other people, like a publisher or other members of your team. It is hard because no-one interested in it and you have to inspire all people around. For this purposes, you need to be inspired yourself and understand how your game will work. Game Design Document here can help you. First, you need to create a one-pager document with all basic concepts, like title, genre, ESRB, and unique selling points (it is what you see on a back of the box with your game). Then you need to create a ten-pager, that contains more detailed information about your game, about a story, about game mechanics, and other stuff. Then Game Design Document comes in with full information of enemies, of their attack patterns, with examples of animations and weapons art, etc. There are examples of all these documents at the end of the book, so when you decide to create it, you have a place to search.
Few words about the characters in computer games. They should look stereotypically (because a player needs to adjust his play style to the character and you shouldn't confuse the player) but act with personal features. If your character is a barbarian he definitely must open doors with a powerful kick, not silently as a mouse. You can also add some traits, like fear of water, or something, but do not forget to add proper animation, when a character meets water.
In the chapter about level design author often mentions Disneyland and attractions in it. Designers of Disneyland worked hard to make attraction excited to visitors and we have something to learn from them. First of all - walking is not a gameplay. If you describe part of your level like "And now the character walks from point A to point B", then you need to remove this part from your game. Second, a level should tell the story, and teach a player. A player can learn how to use this particular mechanic in your game, or how to use weapon, or how to defeat exact enemy, and you need to be sure, that you teach player something. If not - just remove the level from your game. You shouldn't place two levels with a similar environment or/and gameplay next to each other. To see would it be boring or not you can create a beat chart (there are some examples in the book) on a piece of paper and remake your level concepts without wasting a time of developers.
Last useful thing, that I've learned from the book is that you need to make your players hate their enemies. Your bosses should bother them maybe at the start of the level, make their life difficult, so your player would get much more satisfaction from killing the boss, than if he just thing about a boss like about an obstacle.
I will reread this book, I guess multiple times, because I am developing a game now, and will do it (for the rest of my life, I guess), to get some advice and recall some important stuff. If you like games as I like it, you would definitely like this book.