What game were R2D2 and chewbacka playing on the milenium falcon?

There's no specific mention of a game that R2-D2 and Chewbacca were playing on the Millennium Falcon in any Star Wars canon material.

However, we can make some educated guesses based on their characters:

* R2-D2: Being a droid, he might be running diagnostics, accessing data, or playing holographic simulations.

* Chewbacca: He might be tinkering with something, practicing his bowcaster skills, or simply enjoying a moment of quiet contemplation.

It's important to remember that in the movies, the focus is on their roles in the larger mission rather than individual leisure activities.

Ultimately, the answer to what game they were playing is up to your imagination! Feel free to come up with your own fun scenario.