The recently released "Hoops" mode is
Rocket League Trading a great example of this. The mode took the basic concept of Rocket League and transformed it .
into a cars-meet-basketball game. Here's the trailer:This was released entirely for free, but Psyonix partnered with the NBA and released the NBA.
Flag Pack DLC for $1.99, giving paying players 30 NBA flags to add visual flavor to their game. Interestingly, if you go to the Steam store page for this DLC pack, the top comment---as of the time of this writing---reads: "I don't use flags. Bought it to
www.lolga.com support Psyonix."