Emergency 4 (2006) was delisted from Steam and GOG years ago due to expired licenses for vehicle brands and music. Physical copies are scarce and pricey. Here's how to experience the game today, from legal routes to modern alternatives.
Buy 112 Operator on Steam (often under $10). It captures the dispatch/management core of Emergency 4 with modern UI, Steam Workshop integration, and active development. If you must have the 3D unit control of EM4, hunt a used DVD and apply the Freeplay Mod—but accept the legal/ethical gray zone.