My friends and I would play the case study game. It's not really a "fun" game tbh but it worked surpisingly well. We played it anytime we had a spare minute or so (on the bus, walking home, at lunch, waiting for a class to start, even in the line going into the exam). A person names a case study and then you each take it in turns to name a fact about that case. It might be the water level that a river rose to, how many people were injured in a flood, the size of the radius of a volcanic eruption, etc. If you couldn't think of one by your turn, you were out. The winner is the last person standing and they then get to choose the case study so they'd usually pick one that they knew really well or that the other person didn't. Our record was about 35 I think because we all had different facts that we had memorised. (We also played it for English Literature with the quotes game, if you need any help with those as well!)