You are red dude.
You kill other red dudes
Every wave it gets harder and you lose all your money on exchange for health. If your bullets hit any wall, you lost 2 money. If you go below 100 health you gain adrenaline and shoot faster and you take less damage.
And every wave you gain a round bonus.
Please remember I did not make all of this.
Things I added.
I added adrenaline, made your jump larger, added walls, made you lost money on bullet, and made you gain health on waves and on kill, updated the kill message, and more.