Just to add onto what Dryzalar was saying,

Many of the mechanics of the game were glitches to begin with that were just accepted by hakita & co Projectile boosts, dives, super slide jumps are all good examples of mechanics not originally intended

even many OOB's are know and accepted, pipeclip & updoor for example.

in ultrakill the lines between glitch, exploit, and intended mechanics become so blurred that trying to make any real distinction is kinda pointless. There are some things that for one reason or another have been outright banned (ex: shotgun stacking) but thats on a case by case basis depending on what is healthy for the game.

the closest you'll find to glitchless would be inbounds (see post above)

but you can still do 2-4 inbounds if you want to and submit it here, it'd be harder to compete for like top times but your allowed to