I made a functioning gamemode to test how I'm gonna do this.
REMOVED
Basically I'm making a few rules for myself
1. Players shall not need to download any addons besides the gamemode itself
This means that any addons you need will be packaged into the gamemode itself. And will run with the gamemode when you start it. You only need the default addons.
2. Music files and Prints are exempt from the above rule
I don't know how to package music and prints. I could remove this rule if some skilled coder taught me how.
And that's about it. At the moment, the gamemode is fully plug and play! However, once it gets into a more better state, you may be required to download music files.
As the version is currently WIP v1, it's not final.
There is no actual ending yet so you may get lost on where to go.
Once you reach an area that looks like this:

you could consider yourself to have beaten this version. Know that the gamemode is in a WIP (or beta/alpha) state, so there's still much to get hyped for.
Tell me any serious problems you have. All the bricks should load, near the beginning you should get a Butterfly Knife, and eventually you should get a Gun. Zombies should attack you, the ones in the jet room do very little damage, the ones in the car tunnel and outside should do a little more than that. You should eventually stumble on a yellow jeep.
The start of the game is much more boring than it's actually gonna be.