Thanks a lot for the feedback.
The high floating platforms are accessible with just one character, and they give us additional dimensional shards at the end of the level.
In Obscura (the second world), the enemies are intentionally invisible, it's their ability. For example, in Alstrum (the last world) the enemies can pass through everything, but if you get a little close to the enemies in Obscura, you can see them.
The boss is easy if you used the Konami code, but if you used the save I provided, then it's the normal level. I also recommend trying it with the save.
To save a ton of time, I did procedural generation and set enemy damage as a percentage to make it fairer and avoid any imbalance. (levelgen.js)
And yes, it was made without AI.