Video games generate more than US$30 billion in annual sales. This success comes despite changing technological assets and development directions, disappearing funding, and nomadic talent. Stuff happens beyond anyone's control.

And, there is the very nature of video games to consider. Video games straddle the boundaries between technology and art in ways not previously possible. As technology changes, so do the possible stances. Additionally, video games can be about anything, and take any form—from simple puzzles to virtual reality. While they may look the same, no two video games are created the same way. Each has unique challenges, trials, and tribulations.

In short, it is very hard to make a successful video game. Why? And why do people do it? These are the questions Jason Schreier seeks to answer with his book, Blood, Sweat, and Pixels: The Triumphant, Turbulent Stories Behind How Video-Games Are Made. This is Schreier's first book, but he brings long experience reporting about video games for Kotaku, a leading website covering the industry and culture. He has also covered video games for Wired, The New York Times, and Onion News Network.

Schreier suggests five reasons for the difficulty behind making successful video games. First, video games are interactive, they do not move in a liner direction but rather are often propelled forward into their narratives by player choices. Responses to these choices need to be made and rendered in milliseconds. Simultaneously, the game must remember your choices, and actions, and apply them to developing the story forward.

Second, the computer technology upon which video games are based changes constantly. Schreier describes building a video game as driving a train while someone runs ahead of you laying down the track.

Third, the tools used by video game developers are always evolving. Familiar features can be orphaned by new software iterations. Processing and rendering times can lag with the addition of more and more features. Or, tools are no longer supported. Ask those who used Flash for their creative tool how they feel about this.

Fourth, Schreier says scheduling is impossible. Each video game is unique, there is no pattern to follow, nor previous builds of a similar endeavor to gauge the amount of time necessary, or when success might be achievable. Video games are works of art. When is a work of art finished?

Finally, fifth, Schreier says it is impossible to know how "fun" a video game will be until one has played it. "Fun" is a big factor in the success of video games, and often fails the transition from intricate idea to playable, enjoyable user experience(s).

In addition to these difficulties behind building video games, Schreier describes some other factors that run as themes throughout his book: delay, compromises, technology decisions, trade shows driving design and build decisions, and, most importantly, everyone building video games has to sacrifice for a job that seems to never end.

Why do this? Schreier interviewed more than one hundred developers and executives. Each said being on the cutting edge of technology, working with a team of creative people to create something that millions of people may play is an experience unlike any other they can imagine. Any crunch is worth the satisfaction of this potential success.

Blood, Sweat, and Pixels teases out this explanation through its ten chapters, each telling the story behind how a different video game was made. The video games detailed in this manner include Diablo III, Destiny, The Witcher 3, Halo Wars, Uncharted 4, Shovel Knight, Star Wars 1313, Pillars of Eternity, Dragon Age: Inquisition, and Stardew Valley. This selection is interesting, as it includes some of the industry's bestselling games, and some of its most infamous failures.

For example, the chapter focusing on Halo Wars begins with a background story for Ensemble Studios. Based in Dallas, Texas, Ensemble was noted for its Age of Empires real-time strategy games (RTS). But after a decade of making Ages, Ensemble, in 2004, wanted to build a different kind of game.

What genre of game was unclear. Groups within Ensemble promoted different interests, including a massively online multi-player (MMO) and an RTS for consoles.

Ensembles' parent company, Microsoft, was planning to launch Xbox 360, their response to the Sony Playstation. An RTS game for the new console, built by a flagship game company under the Microsoft umbrella, seemed like a good idea.

A group of developers and artists within Ensemble began working on a new RTS. The first problem was how to translate complicated movements within the game world, normally accomplished with a mouse and keyboard, to the console controller featuring only a few buttons. This was new territory, and the solution took months as the team worked through hundreds of different schemes.

Concurrently, a separate team invested thousands of hours developing the mythology, aesthetics, and characters for a new game world.

After several prototypes, Ensemble sought corporate approval, the green light, to move forward. Microsoft executives were laser focused on competing with Sony, conservative, and risk averse. Rather than a new RTS game, they wanted something from an established franchise. If they were going to pay Ensemble to build a game for the new Xbox console, it had to be a Halo game.

Halo, created by Bunjie, in Seattle, was at that time, one of the most popular video games on the planet. Microsoft owned Bunjie, and told Ensemble if they wanted to develop a console RTS game, it had to be a first person shooter, like Halo, which would be easier, and less expensive, to market.

In that one decision, thousands of hours already invested by Ensemble in its conceptualization and prototyping of a new RTS game were wiped away. Microsoft also created an entirely new problem for Ensemble. Even though they were sister companies—Ensemble and Bunjie were both owned by Microsoft—Bunjie had developed the incredibly successful Halo series—they were months away from launching Halo 3—and were not eager to share game assets with Ensemble. Months of trust building were required before Bunjie started sharing the stories behind Halo.

Ensemble developed a new world, and a new story, for Halo Wars, their proposed RTS console game. Every decision, prototype, and story element had to be approved by Bunjie, who maintained ownership of all rights to the Halo franchise.

Not everyone at Ensemble supported the Halo Wars RTS effort. One team continued working on ideas for a MMO. Another team spent a lot of time trying to conceptualize an adventure game. As a result, Halo Wars was understaffed, and fell behind in key areas of the game's development.

Microsoft remained committed and pushed Ensemble to finish Halo Wars. But Ensemble was fractured and cliquish, with members working on different projects even though Halo Wars was the only one with a green light.

Developers and designers split over Halo Wars' directions, features, and play capabilities. The one, understaffed development team, split into two, smaller teams. Ensemble was in turmoil, and worse, in trouble.

In 2008, Microsoft executives announced they would close Ensemble after Halo Wars was released, in four months. Some employees would lose their jobs. Others could become part of an independent new studio focused on creating an online version of Age of Empires. Anyone interested could look for another job.

Those who remained to finish Halo Wars did everything possible to make the game as good as possible. There seemed to be an understanding that Halo Wars would be Ensemble's legacy and those who worked to finish the game wanted it to represent the studio properly.

On 26 February 2009, Halo Wars was released, and Ensemble closed. In 2017, Microsoft hired another developer, Creative Assembly, to make a sequel, Halo Wars 2.

Schreier's telling of Ensemble's journey is an honest assessment of video game development hell. The stories behind the nine other video games are similar. Some are better. Some are worse. But Schreier remains objective throughout each telling and provides an insider story of an industry long noted for its secrecy.

Schreier asked the game developers and executives he interviewed why people willingly sacrifice so much—blood, sweat, and tears—to make video games. Their answers are straightforward: because they want to create something that will be fun to play.

In the end, Blood, Sweat, and Pixels is a tribute to the dedicated people who overcome obstacles greater than those they include in the best video games imaginable in order to provide the rest of us with game play experiences that are immersive, believable, and rewarding.