I have two observations from the challenge game:
1) Starting at new day without malus, the game time runs 10% slower, so 60s becomes 66s in realtime ; After 1st day win (mostly 125 gala credits), so with mallus, the game time runs 10% faster, so 52s becomes 47s in realtime, and even if you clear mallus, 60s become 54s in realtime. So after winning 1st time, trying to win with mallus is extremly tougher, even if you clear it.
2) After you win or lose, trying to hit play again in dialog always freeze the game (latest Firefox, Win10), though the rewards are always awarded. So only clicking go to profile makes sence.
PS: the freeze as posted by previous user happened to me like once in over several hundred games (and no, I won only once with uncleared mallus), so very unlucky to him.