[Geckorian]

Perhaps a combination of rank and play time. Something like each rank comes with a set number of blocks but you also get more the more you play (rough example: regular rank gets 100 blocks and when you go up to the next rank (can't remember what that is atm) you would get another 100 blocks. Plus you earn blocks for each hour played).
In this set up I would think that guest would not get starting blocks and have to earn them by ranking up or via play time.