Timers and Achievements

I've added a timer in the game, so you can see how long you've been able to survive a given match. I'd like to do more with this timer in the form of new achievements (e.g., break X number of blocks in Y minutes) and maybe even leaderboards, but I want to hear from the community first on what y'all think!

I did, however, update the current achievements, so you now have to play / survive on each field for at least a minute. It's still pretty easy to get these achievements if you fiddle with the settings, but that was always the point: I want you to try out different options!