Achieving 'flight' in vanilla, Boom etc.. A new technique? (2025)

Hey there! I'm writing this post to share a technique I discovered in 2022. May it bring mapping joy to those that are interested! I was fiddling around with Mikoportals and realised the player can achieve stable 'flying', including the ability to change directions while in fly-mode, under certain conditions. This kind of flying can be done in vanilla, limit-removing, boom, mbf21 etc.. It kinda works in Zandronum but causes visual artifacts.It might even be done in GZDoom, when using custom frictionless flats, but I haven't experimented with that. (shoutout to the good folks of NERF, that used frictionless flats to great effect in their map set for vanilla conveyors)

Here's a video of an early experiment of mine incorporating 'flight'. (music by @Napsalm) Video with an elaborate example at the bottom of this post.

So what is this? We know that when a player falls onto a floor with a height of -32768 units, the player's vertical position is instantly changed to that of the ceiling, while maintaining momentum (more info on Mikoportals over here and here). Because of Doomguy's lack of air control the player loses all ability to manoeuvre once they fall unto a sector with a -32768 floor. As you can see in this video: the 'falling' that occurs when you enter a Mikoportal appears to stop after a while, seemingly attaching the player to the ceiling ('flying') while maintaining momentum. This by itself can be an interesting effect, if limited. It's been used by many people to create 'vanilla conveyors'.

The 'flying' effect persists when the ceiling height goes up, regardless of the floor height below. So a player can fly upwards if the mapper wants them to. Flying down is not possible: any ceiling lower than their current one will halt the player. Once the player is 'airborne' and has flown up a bit, the floor below the player can be higher or lower at will and the effect will still persist. This means you can make arenas with varying floor heights: not just a straight monotonous hallway. Note: during testing the flying effect sometimes stops when doing this too quickly after achieving flight. I recommend waiting a few seconds until stable flight has been achieved, before changing heights.

Some visuals:

Now the fun part: once the player has gone up a bit in terms of height, the floor can be raised upwards until the height of a sector is 56 units (Doomguy's height). Upon entering a sector with this height, the friction of the floor will slow down and halt the player. The player is able to turn, accelerate and all that jazz, as if walking. Think of it as you dangling from the ceiling by your helmet, and your feet being able to touch the ground and push you around. The flying effect persists and will kick in again as soon as the floor lowers again, even a tiny bit. This means the player only needs to set up the flying process once, and after that they can enjoy a whole map mixed between flight and normal running.

Some more visuals:

I made two serious maps in 2022 and 2023 that use this effect. One for Twofers in mbf21 (releasedtoday, that's why I'm posting this thread today. Have a look here: MAP17) and one for my own limit-removing Ultimate Doom project (to be released SoonTM, video below). I also experimented with various other ideas, such as a vanilla compatible pinball machine and other scenes. I am sure there will be some mappers that can do lots of cool creative things with this technique. Looking forward to what others cook up with this!

Some interesting observations:
-Blood 'falls' upwards upon a monster's death on a floor with -32768 height.
-Projectiles 'fall' upwards when hitting a floor with -32768 height. A rocket exploding on the floor will have the exposion fall upwards as well.
-Monster death sprites that fall (like a Cacodemon) will sometimes start bouncing like a voodoo doll and at times they even achieve 'stable flight'.
-A walking monster (like an Imp) that starts on a floor with -32768 height and then walks upwards, will sometimes start flying themselves upon touching the ceiling. Including all of the initial bouncing. Have a look here for that.
-Monsters can hit the player during flight, changing the player's direction. I think there is a wealth of effects to be explored there, with things like chaingunners or custom dehacked monsters hitting the player (with or without an Invincibility Sphere) and moving the player through a space. Perhaps custom mbf21 projectiles that just move and don't hurt the player? Invisible even? Having one custom dehacked gun that fires non-hurting projectiles behind the player, propelling them forward? You could have a whole map set like that, with ammo for your propulsion being in short supply. Jumpwad but Flywad. The fire extinguisher scene from the movie Gravity, who knows? (right now damage is tied to movement so this is limited, but still) Video of Napsalm experimenting with this (early rough version).
-I haven't experimented with Wind Sectors in Boom yet, perhaps those work to move the player around?

-If you bump into floor monsters while flying, your speed is reduced to zero. But if the monster moves within half a second (or something like that) you often suddenly fly forwards again, at about the same speed you had before being halted. So getting stuck on floor monsters is often not at all as much of a problem in arenas as I was worried about. This sudden gain of speed happens even if the player doesn't get scratched or anything like that.
-I've think I've also observed this behavior when hitting static Things like trees. The player hits them, is halted, slowly drifts to the side ever so slightly and then is launched forward again. More experimentation needed on this one.

Ich bin wie Poog: MAP17 from Twogers

Fly the Friendly Skies: MAP25 from Revenant Hallway

The Word for World is Forest: MAP04 from Portraits of Doom

However Old its Roots: MAP15from Portraits of Doom

Finally here is a video of a map from my upcoming limit-removing cl3 Ultimate Doom map set. The secret map in that set is centered around this type of flight. [SPOILERS!]

Edited February 22 by Peccatum Mihzamiz: first edit 2/3 2025, added observations on 2/22