The human mind is the most powerful game engine - but it can always use some help. This book is meant for developers who want to create games that will evoke richer and more memorable "gameworlds" in the minds of their players. We don't just enter such unforgettable gameworlds when we play first-person 3D RPGs with high-resolution graphics; even relatively simple 2D puzzle or strategy games with 8-bit-style visuals can immerse players in worlds that are beautiful, terrifying, mysterious, or moving, that are brutally realistic or delightfully whimsical. Indeed, good video games can transport us to incredible new worlds. The process by which a particular gameworld emerges is a symbiotic collaboration between developer and player: the game system presents a carefully architected stream of polygons and pixels, which somehow leads the player's mind to construct and explore an intricate world full of places, people, relationships, dilemmas, and quests that transcends what's actually appearing onscreen. Drawing on insights from ontology and philosophical aesthetics, this volume provides you with conceptual frameworks and concrete tools that will enhance your ability to design games whose iconic gameworlds encourage the types of gameplay experiences you want to offer your players. Among other topics, the book investigates: The unusual ways in which a gameworld's contents can "shrink" or "grow" in players' minds, depending on whether the players are mentally positioned within a game's social space, cultural space, built space, or tactical space. The manner in which players' minds spontaneously "concretize" the countless gaps that exist in a game - and how this dynamic explains why so many players still enjoy 8-bit-style games with retro pixel art. The differing ways in which players experience success and failure, danger and safety, good and evil, the future and the past, the known and the unknown, and engagement and retreat, depending on whether a game reveals its gameworld through a "1D" game environment (like that of a text-based adventure), 2D environment (like that of a sidescroller or a grand strategy game with a top-down map view), 2.5D environment (like that of an isometric turn-based tactics game) or 3D environment (like that of a first-person shooter). The powerful way in which players are able to mentally "explore" a gameworld simply by shifting their conscious awareness between different senses, media, ontological strata, and constituent spaces - without needing to travel through the gameworld's terrain at all. Necessary and optional elements of the gameworld - from built areas, natural landscapes, laws of nature, and a cosmogony to the game's player and designer - and their roles in shaping the gameplay experience. How to strategically employ the architectural paradigms of the Cyberspatial Grid, Maze Space, Biomimetic Net, Simulacral World, Virtual Museum, and Protean World when architecting locales within your game, in order to evoke particular kinds of emotional gameplay experiences for your players. The nature of the unique "sixth sense" that 2D games grant to player characters (and players). Simple techniques for helping your 2D game to "feel" more like a 3D game. The differing kinds of immersiveness, interactivity, and determinacy possessed by different types of games and their implications for the gameplay experience. Once you've undertaken this philosophical and artistic journey, you'll never look at your games - or their gameworlds - in quite the same way again.