This paper proposes an Image-Conditioned Gaussian Splat Quantizer (ICGS-Quantizer), which dramatically improves the compression efficiency of 3D Gaussian Splatting (3DGS), enabling high-quality real-time rendering, and enables adaptability to scene changes even after long-term storage. The ICGS-Quantizer leverages inter-Gaussian and inter-attribute correlations and uses a shared codebook across all training scenes to reduce the storage requirements of 3DGS to the kilobyte range while maintaining visual fidelity. Furthermore, it conditionally performs scene decoding based on captured images during decoding, enabling adaptability to scene changes even after long-term storage.