In Get Bit! You play a robot (or in the newer version, a pirate) swimming for your life to escape a robot (or pirate) munching shark. To do this you have to bluff or luck your way into playing different and higher value cards than your opponents. It's a relatively simple game, but that's part of the appeal in my mind.
Get Bit! is quick to pick up and play because the rules are intuitive for the most part. Play a higher card? You're farther from the shark. Closest to the shark? You get bitten. Get bitten? Lose a limb. Lose all your limbs? Sink to the bottom of the ocean and lose the game. The only potentially confusing rule is what to do when two players play the same card. Those players don't move positions except to be next to one another. That means that players should hope to avoid matching the cards of other players, because a match at the wrong time could be potentially disastrous.
While there's not so many cards that card-counting is impossible, but there's still a degree of bluffing involved. Similarly, there's a degree of strategy in deciding if you should allow yourself to get bitten. While it's theoretically possible to survive a game without getting bitten, it's unlikely and grows ever more unlikely the more players are involved in the game. Generally it seems better strategy to choose carefully when you take your bites so that you can play your cards at the most opportune moments.
It's notable that a pseudo prequel to Get Bit! called Walk the Plank! which is just about to finish a Kickstarter campaign (26 hours as this is being written). While the rules are different and neither needs the other to be played, it's pretty cool that Walk the Plank! and Get Bit! can link together.