Go to Campaign,select any mission,activate Famine,Thunderstorm,Tough Luck,Mythic,Cloud,Grunt Birthday Party,and IWHBYD,set scoring to Team,and play.it is a lot of fun,and challenging too.
Don’t really like doing the campaign, especially alone.
I’d probably find custom games with a full lobby a lot more fun. 
I like running to get the Rocket Launcher over and over again.
I enjoy shamelessly dominating when the matchmaking system hilariously matches me up with Warrant Officers and their guests.