If that isn't what you'd prefer, there's also an All Missions campaign which allows you to play through any mission, including custom ones on the hard drive, with any equipment in the game, including some which is multiplayer sepcific. The main campaign, a combination of the vanilla game and The Stetchkov Syndicate, has a carefully crafted unlock system that you can play through with a friend to complete. The broken AI is fixed, cut content has been restored, and every weapon is precisely calibrated to its real world counterpart. I've spent countless hours playing the game, mostly in CO-OP on servers new and old, and there always seemed to be a glimmer of potential that has never been truly realized by games that followed it.
SWAT 4 is a fantastic, if horrendously bugged product. If nothing happens, download the GitHub extension for Visual Studio and try again. If nothing happens, download Xcode and try again. If nothing happens, download GitHub Desktop and try again. GitHub is home to over 50 million developers working together to host and review code, manage projects, and build software together.