With the new build (uploaded today) we brought some fixes to the Survival Mode (both of the arenas).
Because of a bug, popped up some versions ago, it was actually possible to run the Survival Mode in a difficulty other than Hard, as it was originally designed to be.
To be "fair" and allow every player that spent time trying to climb the highest positions of the leaderboard we:
1) fixed that bug: now every Surival Mode game runs in Hard, no matter what's your story mode setting.
2) Increased a lot the number of points: this will allow anyone who want to get back his/her deserved position in the leaderboard to play again and easily overcome those who've got a higher score just because of the wrong difficulty settings (eg. playing at "normal" or "easy").
For any question you might have, please ask in the comments below.