This is Redzur’s first boss level and I like the overall approach. The creator make use of the snowstorm effect, a variety of tiles to create an interesting level. The level feels approachable to new players and has good use of checkpoints, but still has some challenges.
I appreciated the use of gems to add some extra difficulty for advanced players, and I think this could have been done even more with some extra vertical platforms. Given how linear the level was, some extra challenges for advanced players would really make it pop. Same thing with the intial door switch, this could be changed into a minor challenge of some sort.
Ironically, the hardest part of the level, was the air platform before the first checkpoint. I must have died 3 times falling into the vacrat, which was a little frustrating because of the checkpoint being right after that.
As for future improvements to the level, there are a few things I think that could be done to round it out. First, I think the snowstorm effect could be turned off when entering the boss fight. This would help to signal that you are in a different area. Second, I think some more hinting on the level secrets would be really nice. I fell into the hidden gem area and never noticed the hidden blocks until the second run through. Some gems to hint at these things could help make the player feel smart.
Overall, a great starting level!