AI is reshaping the game development prototyping pipeline by addressing the core contradiction between speed and visual fidelity. Traditionally, developers used gray boxes and placeholder graphics, which quickly verify core mechanics but fail to provide key information such as visual language, character proportions, and animation texture. The developed platform reduces the character creation cycle from several days to just a few minutes, enabling the use of real sprite sheets during prototyping. A complete character set including walking, idle, and attack animations can be generated in around 20 minutes. This allows developers to generate a testable character in the morning, run gameplay tests in the afternoon, and create a revised version the next day. The platform AI Sprite Generator positions itself as a bridge between prototyping and production, generating game-ready characters quickly for use during development, then refining or replacing them as the project matures. In a practical test, a basic platform game character with a walking cycle and a jump animation was exported and imported into a Unity project, with the entire process from startup to real-machine gameplay taking only 1 hour. After noticing the jump arc felt unrealistic and floaty, the character’s proportions were adjusted to make the body slimmer and more compact.