For those who grew up in the Atari era, when primitive video games were first coming on the scene, the key to success at most electronic games was simple: beat the game, or at least get a high score. Games were repetitive, fairly simple, and tended to set strict limits on player behavior. In many of the most popular side-scrolling games, movement was only allowed from left to right. Players had to go where the game designers wanted them to go. The only real choice was figuring out what to do along the way. The rise of 3D technology helped change that by recasting games as visits to virtual environments. Even in their most rudimentary form, the inclusion of virtual worlds gave players a new form of agency, because it gave them something to explore. And over the last 25 years, writes Peter Suderman, video game virtual environments have grown bigger and richer, more detailed and more complex, filled with big crowds and tiny details, and, in the very best games, a sense of practically limitless possibilities for play and exploration.