This mod is attempting to revive the Modern Warfare Remastered PVP scene. Though you have to own the game, it allows for a fairly simple install to give you that feeling you had back in 2007 when you were pwning noobs until 2AM and disparaging a random gamer's mother. They've got the install instructions on the site (which this links to) so you can either set up your own server or play on others with custom rules. And you can unlock everything. Have fun!