Just a rant to complain :P
Started playing through the arena and exited. once I returned I only then discovered that it does not save your progress. Now i know you can still get the achievements for round 5 and 30 even if you die (died at round 4 but kept playing) and I don't really care about the leaderboards. I just don't see myself being patient enough to run through 30 rounds in a row. I guess that's at least one achievement I shant be getting (the other being Dark Mode - no thanks).