diff --git a/src/agents/diffuse.rs b/src/agents/diffuse.rs
new file mode 100644
index 0000000..a656f45
--- /dev/null
+++ b/src/agents/diffuse.rs
@@ -0,0 +1,105 @@
+use super::PlayerAgent;
+use crate::util::Symb;
+use rand::Rng;
+use std::num::NonZeroU8;
+
+/// A simple "operator diffusion" MINIMIZER agent.
+///
+/// Tries to keep operators as far apart as possible, denying large numbers.
+pub struct DiffuseAgent {}
+
+impl DiffuseAgent {
+	/// Place a symbol on the board.
+	/// Assumes `symb` is not already on the board
+	fn step_symb(&self, board: &mut crate::board::Board, symb: Symb) {
+		if board.contains(symb) {
+			panic!("Called `step_symb` with a symbol that's already on the board!")
+		}
+
+		// Fill distance array with largest possible value
+		let mut dist = [board.size() + 1; 11];
+
+		// Set up initial distances
+		dist[0] = 1;
+		*dist.last_mut().unwrap() = 1;
+		for (i, o) in board.iter().enumerate() {
+			if let Some((s, _)) = o {
+				if s.is_op() {
+					dist[i] = 0
+				}
+			}
+		}
+
+		let mut did_something = true;
+		while did_something {
+			did_something = false;
+			for i in 1..(dist.len() - 1) {
+				let l = dist[i - 1];
+				let r = dist[i + 1];
+
+				let new = (l + 1).min(r + 1);
+				if new < dist[i] {
+					did_something = true;
+					dist[i] = new;
+				}
+			}
+		}
+		let mut max_dist = *dist.iter().max().unwrap();
+		println!("{:?}", dist);
+
+		'outer: loop {
+			for i in 0..11 {
+				if dist[i] >= max_dist {
+					if board.play(i, symb) {
+						break 'outer;
+					};
+				}
+			}
+			max_dist -= 1;
+		}
+	}
+
+	/// Called when we're out of symbols
+	fn step_number(&self, board: &mut crate::board::Board) {
+		let mut rng = rand::thread_rng();
+		let n = board.size();
+
+		let mut c = rng.gen_range(0..n);
+		let mut s = {
+			let n = rng.gen_range(0..=9);
+			if n == 0 {
+				Symb::Zero
+			} else {
+				Symb::Number(NonZeroU8::new(n).unwrap())
+			}
+		};
+
+		while !board.play(c, s) {
+			c = rng.gen_range(0..n);
+			s = {
+				let n = rng.gen_range(0..=9);
+				if n == 0 {
+					Symb::Zero
+				} else {
+					Symb::Number(NonZeroU8::new(n).unwrap())
+				}
+			};
+		}
+	}
+}
+
+impl PlayerAgent for DiffuseAgent {
+	fn step(&mut self, board: &mut crate::board::Board) {
+		let symb = [Symb::Minus, Symb::Times, Symb::Plus, Symb::Div]
+			.iter()
+			.filter(|x| !board.contains(**x))
+			.next();
+
+		// No symbols available, play a random number
+		if symb.is_none() {
+			self.step_number(board)
+		} else {
+			self.step_symb(board, *symb.unwrap())
+		}
+	}
+}
diff --git a/src/agents/mod.rs b/src/agents/mod.rs
new file mode 100644
index 0000000..39bceeb
--- /dev/null
+++ b/src/agents/mod.rs
@@ -0,0 +1,11 @@
+mod diffuse;
+mod random;
+
+pub use diffuse::DiffuseAgent;
+pub use random::RandomAgent;
+
+use crate::board::Board;
+
+pub trait PlayerAgent {
+	fn step(&mut self, board: &mut Board);
+}
diff --git a/src/random.rs b/src/agents/random.rs
similarity index 95%
rename from src/random.rs
rename to src/agents/random.rs
index ed7ede6..5052a52 100644
--- a/src/random.rs
+++ b/src/agents/random.rs
@@ -1,8 +1,7 @@
-use std::num::NonZeroU8;
-
+use super::PlayerAgent;
+use crate::util::Symb;
 use rand::Rng;
-
-use crate::{util::Symb, PlayerAgent};
+use std::num::NonZeroU8;
 
 pub struct RandomAgent {}
 
diff --git a/src/main.rs b/src/main.rs
index b1ec09c..b27f7ae 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -11,22 +11,16 @@ use termion::{
 	raw::IntoRawMode,
 };
 
+mod agents;
 mod board;
-mod random;
 mod util;
 use board::Board;
 use util::{Player, Symb};
 
-use crate::random::RandomAgent;
-
-pub trait PlayerAgent {
-	fn step(&mut self, board: &mut Board);
-}
-
 fn play(
 	stdout: &mut StdoutLock,
 	player_max: bool,
-	computer: &mut dyn PlayerAgent,
+	computer: &mut dyn agents::PlayerAgent,
 ) -> Result<Board> {
 	let mut cursor = 0usize;
 	let cursor_offset = 10usize - 1;
@@ -88,6 +82,7 @@ fn play(
 			break;
 		}
 
+		// Player turn
 		let stdin = stdin();
 		for c in stdin.keys() {
 			print_board = match c.unwrap() {
@@ -112,10 +107,10 @@ fn play(
 				Key::Char('8') => board.play(cursor, Symb::Number(NonZeroU8::new(8).unwrap())),
 				Key::Char('9') => board.play(cursor, Symb::Number(NonZeroU8::new(9).unwrap())),
 				Key::Char('0') => board.play(cursor, Symb::Zero),
-				Key::Char('a') => board.play(cursor, Symb::Plus),
-				Key::Char('s') => board.play(cursor, Symb::Minus),
-				Key::Char('m') => board.play(cursor, Symb::Times),
-				Key::Char('d') => board.play(cursor, Symb::Div),
+				Key::Char('+') => board.play(cursor, Symb::Plus),
+				Key::Char('-') => board.play(cursor, Symb::Minus),
+				Key::Char('*') => board.play(cursor, Symb::Times),
+				Key::Char('/') => board.play(cursor, Symb::Div),
 				_ => false,
 			};
 			continue 'outer;
@@ -129,7 +124,7 @@ fn main() -> Result<()> {
 	let stdout = HideCursor::from(stdout().into_raw_mode().unwrap());
 	let mut stdout = stdout.lock();
 
-	let mut agent = RandomAgent {};
+	let mut agent = agents::DiffuseAgent {};
 	let a = play(&mut stdout, true, &mut agent)?;
 	if a.is_done() {
 		println!(
@@ -147,7 +142,7 @@ fn main() -> Result<()> {
 		return Ok(());
 	}
 
-	let mut agent = RandomAgent {};
+	let mut agent = agents::RandomAgent {};
 	let b = play(&mut stdout, false, &mut agent)?;
 	if b.is_done() {
 		println!(
diff --git a/src/util.rs b/src/util.rs
index d6f0a50..3dade5a 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -59,9 +59,9 @@ impl Display for Symb {
 
 impl Symb {
 	/// Is this symbol a plain binary operator?
-	pub fn is_binop(&self) -> bool {
+	pub fn is_op(&self) -> bool {
 		match self {
-			Symb::Div | Symb::Plus | Symb::Times => true,
+			Symb::Div | Symb::Plus | Symb::Times | Symb::Minus => true,
 			_ => false,
 		}
 	}