I think that a feature where you could play against one of your friends that are online would be nice. I've been trying to play against my brother, and random people keep joining, and we're unable to play a game together.
Level 50 is really hard. I'll try to explain.
Make it so that the last 8 gates are as follows:
1-2-3-4-5-6-7-Deactivated.
It might not seem to work at first based on the order you open them in, but wait a couple minutes and you should complete the level and get the badge.
Turns out that the impossible badge is possible after all.
I find it funny that all of the High Scores for Achievements are greater than the number of possible achievements.