It may seem an odd subject to focus on, as jumping doesn't seem to be very important on the face of it – cut it out of a game, though, and it can make a huge difference. Games in which players can’t jump, or at the very least dodge or roll, can seem painfully slow, dull and static. Games in which players can jump around and use that movement to interact with the environment can seem immeasurably more fun because of it.
Take Half-Life 2
, for example. It’s a game which nearly everyone would agree is well-made, decently written, fun and fast to play through. Now cast your mind back to the first scene in Kliener’s lab, where Gordon is first properly introduced to his allies, where the plot is given its first proper push and where you’re gifted with the HEV suit again. It’s a busy sequence; lots to do, lots to take in. You’d expect most players to pay close attention, at least the first time around.
Instead, every single player I know spends most of the time jumping around. Sometimes they try to jump on the scenery or knock over objects, other times they just leapfrog around the room when a simple stroll would suffice.