diff --git a/src/cli/cli.rs b/src/cli/cli.rs
index 6d452ed..34de086 100644
--- a/src/cli/cli.rs
+++ b/src/cli/cli.rs
@@ -40,10 +40,16 @@ pub struct SurfaceProbabilityMeasureCli {
 
 #[derive(Subcommand, Debug)]
 pub enum PCM {
+    /// Traditional DLA model in a fixed-size 2D grid
     Initial(InitialCli),
+
+    /// Traditional DLA model in a fixed-size 2D grid with a probabilistic sticking component
     StickProbability(StickProbabilityCli),
 
+    /// Traditional DLA model in unbounded 3D space with probabilistic sticking
     Grid3d(KDStickProbabilityCli),
+
+    /// Traditional DLA model in unbounded 3D space with probabilistic sticking and off-axis walks
     Grid3dOffAxis(KDStickProbabilityCli),
 
     Hex(StickProbabilityCli),
@@ -59,13 +65,13 @@ pub struct ModelCli {
     #[command(subcommand)]
     pub preconfigured_model: PCM,
 
-    #[arg(long)]
+    #[arg(long, help = "Set the maximum number of ticks the system will run before exiting, will still produce data after this has been reached.")]
     pub max_frames: Option<usize>,
 
     #[arg(short = 'N', long)]
     pub max_particles: usize,
 
-    #[arg(long, short)]
+    #[arg(long, short, help = "Specifying a seed allows for deterministic runs (when combined with other parameters such as -N)")]
     pub seed: u64,
 
     #[arg(value_enum, short, long, default_value_t = OutputFormat::Positions)]
@@ -74,6 +80,9 @@ pub struct ModelCli {
     #[arg(value_enum, short, long)]
     pub output: PathBuf,
 
+    #[arg(long, default_value_t = false, help = "If the output file already exists, skipping running. Useful when running deterministically.")]
+    pub preserve_existing: bool,
+
     #[arg(short, long)]
     pub notify_every: Option<usize>,
 }
diff --git a/src/main.rs b/src/main.rs
index d922842..7fa1688 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -17,7 +17,7 @@ use crate::system::spaces::square_grid::{Grid2D, Grid3D};
 use crate::system::spaces::VectorStorage;
 use crate::system::spawner::UniformSpawner;
 use crate::system::sticker::{ProbabilisticSticking, SimpleSticking};
-use crate::system::walker::{DiagonalRandomWalker, LocalRandomWalker};
+use crate::system::walker::{DiagonalRandomWalker, LocalRandomWalker, Walker};
 
 mod system;
 mod surface_probability_measure;
@@ -26,6 +26,11 @@ mod cli;
 fn main() {
     let cli = ModelCli::parse();
 
+    if cli.preserve_existing && cli.output.exists() {
+        println!("Skipping model execution as output file '{}' already exists", cli.output.to_str().unwrap());
+        return;
+    }
+
     println!("Running: {:?}", cli);
 
     match cli.preconfigured_model {