Hey,
thanks for the feedback! We have already an idea of how to extend the gameplay loop, which we will try to add after the rating.
For the multiplayer, it's best if you grab a friend and challenge him. At the moment the game doesn´t have a big player base. And due to simplicity at the moment you can only join a match if it didn't start. We will also change that after the rating and once we overhauled the gameplay loop.
It does affect it. But this depends on the platform you play on. Currently, we only support saving on windows only, why we decreased max level on WebGL to 10.
Difficulties should normally give you more movement speed but in a trade for a better-needed reaction time and less time to press the keys. But I noticed some issues which resulted in strange behaviors. But since the difficulties might change completely in the rework we will hold it and review it after the rework.
Thanks again!