For many, the golden age of Crossfire was the era of the M4A1-S, AK-47, AWM, and the original Black Widow map. Modern CF is cluttered with neon skins, flying mechs, and chaotic UI. Private servers like Crossfire Europe or CF Old School freeze the game in time, offering the classic HUD, old sounds, and the original slow-paced tactical gameplay that made the game famous.
However, prosecution of players is virtually unheard of. Smilegate typically targets server owners hosting in countries with lax copyright laws (Brazil, Russia, Vietnam). You will not go to jail for playing, but your official CF account could be permanently banned if the private server launcher scans your registry.
Private servers operate by reverse-engineering the game's server-side protocol or utilizing leaked source code.