From the campaign:
Geared is a 2-4 player bike building card game where players must race against each other to put together as many bikes as they can and be the first one to earn 1000 points. However, watch out for other players who may try to sabotage your bike builds by removing, stealing, or swapping your parts. Whether or not the parts are all the same level determines how much a build is worth. The higher the level of parts, the more points you could earn. You can focus on playing one Parts Card at a time, or you could build a matching bike in your hand and play a build combo to lay it all down at once. Once a build is complete, its Parts Cards can not be used again. This makes it important to complete a bike only when you know its Parts couldn't be used for a better build. In order to build the best bikes and earn the most points, you must be smart about when and how you lay parts down.