diff --git a/day11/src/main.rs b/day11/src/main.rs
index 44fa209..0b5469e 100644
--- a/day11/src/main.rs
+++ b/day11/src/main.rs
@@ -7,15 +7,16 @@ mod board_metadata;
 mod game;
 mod rules;
 mod rules_easy;
+mod rules_hard;
 
 use binary::State;
 use game::Game;
+use rules::Rules;
 use rules_easy::RulesEasy;
+use rules_hard::RulesHard;
 
-fn main() {
-    let stdin = io::stdin();
-    let lines: Vec<_> = stdin.lock().lines().map(|line| line.unwrap()).collect();
-    let mut game = Game::from_input::<RulesEasy>(&lines);
+fn solve<T: Rules>(lines: &[String]) {
+    let mut game = Game::from_input::<T>(&lines);
 
     //game.print_board();
 
@@ -31,3 +32,11 @@ fn main() {
     game.print_board();
     println!("Board stabilized at {} occupied seats", game.get_count_of_cells_for_state(State::SeatOccupied));
 }
+
+fn main() {
+    let stdin = io::stdin();
+    let lines: Vec<_> = stdin.lock().lines().map(|line| line.unwrap()).collect();
+
+    solve::<RulesEasy>(&lines);
+    solve::<RulesHard>(&lines);
+}
diff --git a/day11/src/rules_hard.rs b/day11/src/rules_hard.rs
new file mode 100644
index 0000000..dc2a6ff
--- /dev/null
+++ b/day11/src/rules_hard.rs
@@ -0,0 +1,47 @@
+use enum_map::EnumMap;
+use ndarray::Array2;
+use strum::IntoEnumIterator;
+use crate::binary::{Direction, State};
+use crate::board_metadata::{BoardMetadata,CellLocation};
+use crate::rules::Rules;
+
+fn find_neighbour(cell_location: CellLocation, direction: Direction, board_metadata: &BoardMetadata, original_states: &Array2<State>) -> Option<CellLocation> {
+    let mut location = cell_location;
+    loop {
+        match board_metadata.get_neighbour_location(location, direction) {
+            Some(new_location) => match original_states[new_location] {
+                State::SeatEmpty | State::SeatOccupied => {
+                    return Some(new_location);
+                },
+                _ => {
+                    location = new_location;
+                },
+            },
+            None => {
+                return None;
+            },
+        }
+    }
+}
+
+pub struct RulesHard {}
+
+impl Rules for RulesHard {
+    fn get_next_state(current_state: State, neighbour_counts: EnumMap<State, usize>) -> State {
+        match current_state {
+            State::SeatEmpty => if neighbour_counts[State::SeatOccupied] == 0 { State::SeatOccupied } else { State::SeatEmpty },
+            State::SeatOccupied => if neighbour_counts[State::SeatOccupied] >= 5 { State::SeatEmpty } else { State::SeatOccupied },
+            other => other
+        }
+    }
+
+    fn get_neighbours(cell_location: CellLocation, board_metadata: &BoardMetadata, original_states: &Array2<State>) -> EnumMap<Direction, Option<CellLocation>> {
+        let mut neighbours = EnumMap::new();
+
+        for direction in Direction::iter() {
+            neighbours[direction] = find_neighbour(cell_location, direction, &board_metadata, &original_states)
+        }
+
+        neighbours
+    }
+}