OMG I actually beat it! I didn't expect to be able to.
The vibes are immaculate. With the cool chill music in the background and the cool dark cave with glowly lights and birds flying around. The art is also really well done.
I think the game as a concept is actually a great concept, with the legendary, simple but engaging gameplay mechanics that people strive for. It's really quite hard to find a simple but engaging concept and I think this game handles it quite well, with the sword slash mechanic being a simple one but one with a lot of depth. The name is also quite clever.
I do think there are a few things that did make me quite frustrated. It's a bit hard with these kinda games since Jump king in it of itself is very frustrating by design. But I think 3 things I found frustrating are:
1) You can die from hitting the ground, perform a slash and then die after the slash is over. This kind of "fake out" where I think I successfully slashed the ground, and then died, was somewhat frustrating
2) I feel like ERB's hurtbox might be a bit too large. I think sometimes I would clip a bit of ERB's hair or something similar and die. I think shrinking the hurtbox a little bit to favor the player can help ease frustrations.
3) There are some comments about making it so you only die from hitting the ground instead of hitting the ceiling. That could be interesting and ease frustrations, but I feel like the game as is, is designed around dying from hitting ceilings. So for this I think it's fine, as you would need to change how the game is designed to accomodate that. I think maybe part of why it is frustrating is that it doesn't look like you should die from ceilings. Maybe changing some blocks to be spiky/lava/dangerous could make it more clear?