The Challenge of Prose: Realism vs. Plot

Often times while writing "The Storm Upon Us (Working title)" I've had difficulty in balancing how  I want the story to play out with the necessity of keeping the story slightly believable. I've tried to stay far away from anything that might cause my story to dissolve into a Walking Dead knockoff,  but sometimes that's difficult.

Example: The player is transporting ammunition from checkpoint to checkpoint driving a truck when he comes across a small horde of Limblex (Zombies missing limbs that can are fast-moving due to a high virus concentration in their bloodstream). The horde chases him off the trail and he runs into a tree. At this point the player is forced to choose between attacking the horde and fleeing the vehicle. Now arguably, hitting a large tree while traveling at an extremely fast speed in a small vehicle is probably enough force to kill someone at the very least, but because I need the plot to move along, they are completely unharmed. If they player tries to fight, the vehicle explodes and they die. If they flee, they are rescued by a fellow militia member who has been holed up in the woods for several months.

Current Family Plans

So I did some brainstorming on how I could incorporate my family into my project and I decided there were some creative ways they could assist me.

1) I will be interviewing each member of my family about how they would feel in different situations in a hypothetical zombie apocalypse and using their responses as story ideas

2) My mom is a Music Ed Teacher for K-8 students in District 15 and specializes in bringing music technology into her classroom. One of the programs she uses most to compose is Finale Notepad. I'm going to ask her to compose a short theme piece on what a zombie apocalypse might sound like if put into music.

3) My family will serve as my lab rats for this story and I will see which paths they take most often while playing through it in it's beta stages.

More Clarity on CYOCYOA

"Choose Your Own Choose Your Adventure" is the website I have chosen to write my story with as it requires the least amount of HTML coding to use. I simply add "branches" for each different choice and then type up the paragraphs for it. Right now the plot takes two different directions depending on the player's choices. You either are part of a "last stand" against a large horde on the roof of a warehouse, or you and your militia members help survivors escape to a boat that will take them to a safe zone. Sidequests include trying to find members of your estranged family and trying to find the missing scientist who has developed a cure. Right now most of the endings are negative, usually involving the player being eaten because of a dumb choice.