Here's a level I made. It took me a long time and tons of tweaking. It actually got to the point where it was on hold for months. I would guess the total amount of time it took to make was in the dozens of hours (not to say it's nearly good enough to warrant it).

Level name: Heaven & Hell

Concept: A level where Mario descends through Hell and then returns to Heaven. Along the way you fight the same enemies, but with different variants (one "Hell" variant and one "Heaven" variant). The hell level is a challenging, scary, platforming experience, whilst the heaven portion is more like a schmup (albeit very basic).

Course ID: 994-V7Y-1SF

My newest course created over the past weekend, Updated to OP:

Dragon Fire Returns

Course ID: 5CG-BTY-R1H

Description: The King's Treasure has been stolen by an Evil Dragon. It is up to the daring Prince to reclaim it. Enter 3 strongholds protected by the Dragon and his Hatchlings. This is the next game in my "Returns Series" comprising of recreations of 80's classics. "Dragon Fire" was ported to many systems in the 80's, but I played it on my TRS-80 Color Computer 2. So, this would also be the 2nd of my TRS-80 CoCo2 recreations (the first being "Downland").

Likes: 0

Played By: 1

Clears: 0

Attempts: 6

Clear Rate: 0.00%

World Record: 0:00.00

Uploaded: 3/22/2020

It's only been played by 1 person as of my uploading it last night.  "First Clear" is up for grabs on this one.  

Sounds like a very cool concept.  I'll make sure to check this out soon!

I haven't gotten through "Heaven & Hell" yet, but I did try out your other levels as well.  I finished "Death Proof" and left a Like on it.

Continuing with adding screenshots for my Course listings.  These are from "GI Joe:  Escape from The Pit".

GI*Joe: Escape from The Pit
Level Code: RXP-VBP-63G
Description: You start off at the lowest level of GI*Joe's secret underground base, The Pit. Suddenly, Cobra Troops bore their way in through the walls. Fight your way up to the surface, emerging through the Motor Pool above. Fight your way through the invading Cobras on the surface, making sure to blow up the bridge during your daring escape.

Cool level! You have a real knack for good imaginative visual design : D 

Thanks!  Being able to orientate the sub-world for vertical scrolling gave me the inspiration to create an "escape" course where you start off deep underground and have to work your way up to the surface.  An homage to GI Joe where their headquarters, The Pit, has been infiltrated by Cobra seemed like a perfect fit for that concept.  This actually occurred in the GI Joe Marvel comic #53 which I read as a child.  General Hawk and some top military brass had to fight there way out through hordes of B.A.T.'s (Battle Android Troopers).  Having Cobra bore their way in from below was inspired by Cobra's infiltration of The Pit in the movie "GI Joe: The Rise of Cobra".  I used a blueprint of The Pit from the first issue of the Marvel comic as a baseline for what should be on each level and then crafted my own rendering of those themes.  For instance, Level Three was said to have a training area, so I crafted a Target Range and Obstacle Course.  On the surface, I tried to craft as many recognizable Cobra vehicles to take part in the attack as possible.  There are "Trubble Bubbles", a F.A.N.G. Helicopter, a H.I.S.S. Tank, and multiple Rattler Jets.  The Boss fight against Boom Boom in the garage is supposed to be "Big Boa" who was the trainer of the Cobra troops.  I threw in the bridge demolition at the end to bring the tension of the escape to a final climax.

Updated to Op, my newest creation:

Smurf Rescue (Coleco Vision)

Course ID: PY3-JQV-7DG

Description: My recreation of Smurf: Rescue in Gargamel's Castle which was ported to a number of systems in the early 80's, but I played it on my Coleco Vision. Smurfette has been kidnapped by Gargamel. Your Smurf must leave Smurf Village and travel through a forest and cave to reach Gargamel's Castle to rescue her. I recreated the game at one of it's higher levels involving more difficult jumps, bats, and spiders.

Likes: 1

Played By: 8

Clears: 2

Attempts: 33

Clear Rate: 6.06%

World Record: 1:08.898

Uploaded: 3/26/2020

*First Clear has already been achieved on this one.  But, if you are looking for a "First", my "Dragon Fire Returns" course uploaded a few days ago still remains uncleared.

My latest course has been updated to OP.  I spent the weekend on this and think it came out really good for the theme I was going for.

Mega Man Returns

Course ID: TT2-WHN-PVF

Description: Another entry in my "Returns" series. Play as Mega Man and assimilate the powers of 4 out of control Robot Masters before the ultimate confrontation with Dr. Wily. In classic Mega Man style, you can battle the Robot Masters in any order you choose.

I literally just finished the clear checks on my lunch break and uploaded it just now.  So, there isn't any "plays" information as of yet.  Which, means First Clear is available.  Each Robot Master has a Red Key Coin that creates the Key to the final boss fight "Dr Wily".  I put an extra checkpoint after you use the Key, so that dying against the final boss doesn't force you to fight the 4 Robot Masters all over again.  If you play and finish the course, let me know what order you fought the 4 Robot Masters in.  I had my own preferred order.  

Next batch of screenshots.  This is from my "Dragon Fire Returns" course which was a recreation of Imagic's 80's port of "Dragon Fire" to the TRS-80 Color Computer 2.

Dragon Fire Returns
Course ID: 5CG-BTY-R1H
Description: The King's Treasure has been stolen by an Evil Dragon. It is up to the daring Prince to reclaim it. Enter 3 strongholds protected by the Dragon and his Hatchlings.