Given that there are multiple .lvl files, as well as a .wld, this qualifies as an Episode.
Alright so I'll just briefly skim over this, as, quite frankly, there isn't much to this episode. Do I have anything positive to say? Yes. It's playable. Barely. But I don't know if I can add anything to this.
Apart from partially terrible graphics choices (aka beach), the world was just littered with oversights and bugs and felt incredibly rushed. I won't delve further into the design aspect of the game as you're new and I didn't expect you to post anything mindblowing with this level. Anyways...
You might be thinking (Bugs? What does she mean by that?) well, I want to draw your attention towards the first level's midpoint. You have placed some wooden pencil blocks on a layer, which move up and down, allowing the player to advance. That's the idea. However, in SMBX, when "Restart Last Level On Death" is selected, automatically starting events do not activate. Ergo: The level is unplayable, unless you play them seperately in the editor (aka barely playable).
Over to oversights. I have two for this one:
First, you can skip the "wake up from dream" axes by jumping. Add nogravity=1 to the code and make a wall of them, set them on their own layer which gets hidden once the event on death is activated (if you don't hide them the text might proc repeatedly).
Secondly, you can one-shot Bowser by holding a veggie against him. RIP in Kill.
Even the story felt lackluster. There was not even a closing dialogue at the end of the game, and a Swap Mushroom was the item I least expected to be used to end the game.
When playing the game outside the Level Editor, I quickly grew tired of the fact you pushed what could've eventually been 3-4 levels into one level without a worldmap and with a checkpoint after 3/4 of the adventure (AKA no saves no checkpoints no reward). The lack of powerups and unfair path near the Hammer Bro don't help with keeping the player invested. I ultimately used sonicstooslow to bypass beach and grass areas just to get another shot at the Hammer Bro.
Lastly, Redigit, when making this game, misplaced the SMB2 Bridge Piece in the SMB3 Misc Tab (The one you used next to the 1-Up in the grass section). This is a personal nitpick but I suggest you use the SMB3 Bridge Piece in SMB3 Levels. It can be found right next to the SMB2 one.
I won't give this a score as of now, since it wouldn't add much to this review. I could go on about rushed level design, poor NPC, coin, BGO, powerup and checkpoint placement some more, but I think you get the point.
I'm surprised it took me until the grass part to realise that Mario is green. And that the mushrooms aren't Poison Mushrooms.