Hey Sneca,
I actually like how the old school games did cheat codes. It feels pretty satisfying when you memorize them, like the guns cheat in grand theft auto 3 for example. The point of the codes being so long is so it doesnt happen accidentally through regular play and so that you cant smash on the buttons on the controller and get a cheat code. They're made with the controller in mind and dont actually translate so well for the mouse and keyboard so I added these simple three key combinations that should be easy to remember too.
Mouse and Keyboard Cheats
Just press all three keys at the same time:
Invulnerability: I N L
Big Bullets: B Y G
Big Head Mode: B I G
Max Resources: R S C
Max Hearts: H R T
Max Ammo: G U N
Herd Up: H U P
Herd Down: H D M
Max Gas: G A S
All Survivors: S U V
All Shards: O R B
Hope this helps,
Rafi