That is physically impossible without destroying the core assets of the game.
The full game, including its numerous DLCs (downloadable content), can easily balloon to over 15 GB to 20 GB. Even the base game requires roughly 4 GB of storage. This has led to a massive search trend on forums like Reddit, Ocean of Games, and FitGirl Repacks: cities skylines highly compressed 500mb
The game’s simulation engine, vehicle models, building assets, and sound design simply require data. You can strip it down to a "Lite" version of roughly 1.5GB, but 500MB is a mirage designed to download malware onto your computer. That is physically impossible without destroying the core