EDIT - THIS GLITCH HAS BEEN PATCHED - RIP IN PEACE SUPER SANIC SPEED WALKING IN FORGE. YOU WILL BE MISSED 
File is in my content browser if anyone wants it. If you can get it working, please tell me how to, or make a youtube video on it⦠or something like that. Below is original text.
Since Iām now a marine and can actually post evidence that this glitch exists, Iād figure Iād scrap the old thread and just make a new one, since itās somewhat outdated in my opinion. (that and itās kind of a mess.)
I was just mindlessly messing around in forge with random maps I found. I was lagging really badly (Assuming itās because of my internet), so logically, I decided to restart the game. When the game restarted, I was still experiencing lag in forge mode. So I reset again, and when it loaded, I decided āscrew it, Iāll see how these maps work in custom games.ā So when I went out of forge mode, into custom games, the āForgeā gamemode was selected by default. Out of curiosity, I checked the settings in the game mode, and the only option there was āSave a copyā. (And yes, of course thatās what I did) And when I reset for the 4th time (out of curiosity again) I found with trial and error, you can play āForgeā while in the custom games lobby. (Not the original copy, the one you saved.) And⦠well⦠mess around to your hearts content.
Ok back story over. What I found essentially in a nutshell, is that forge can be played in custom games (if your internet/connection to the halo 5 servers is slow enough and you manage to save it in time.)
As for playing in forge again, the original āForgeā file is used until you load the one that you saved. (The one made by 343 is the one loaded by default. When you use the new/saved file, that file is used instead. The only way to fix this is by restarting the game.) When I tested it It also inherits traits from the game you loaded last (Minus weapon starts.) So for example, If I loaded a game with a huge speed boost prior to loading the forum, it seems that I keep that speed boost. If I set the kills to 200, the āForgeā is set to 200 kills to win, and so on. You can also NOT save maps using the forge you saved in your files. (Only the original file by 343i works for saving maps)
I still have the forge file saved, (and screenshots have been attached as proof⦠I could even rename it, so thatās what I did. Not shown in the screenshot though.)
So I guess my question is this - Is it gamebreaking? And if so, will there be a hotfix for it?
(No, Iām not going to share the forge file with anyone unless they are forums staff/admins for now, because despite me messing around with it in Infection/slayer mode, I canāt guarantee that it will damage game files if traits are inherited from other gamemodes (like CTF), and I canāt guarantee that it isnāt game breaking. Last thing I want to be known for is some guy that watched the world burn. If it is found out that this is NOT gamebreaking/file damaging in any way, then I donāt see the harm in making the forge file public, however Iām not going to give the file to normal players until I know for a fact that it can in no way, shape, or form damage the gameās files/profile sync.)
Anyways, hereās that evidence I mentioned earlier.
Proof that itās possible/proof that the glitch exists.