diff --git a/.gitignore b/.gitignore
index 7d0d0d0..f4812e7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,5 @@
 target
 *.sw*
+
+# Developers may wish to generate JSON replays of bot games and store them in /replays/
+/replays/
diff --git a/Cargo.lock b/Cargo.lock
index b972c22..fb1192b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -41,6 +41,12 @@ dependencies = [
  "unicode-width",
 ]
 
+[[package]]
+name = "itoa"
+version = "1.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fad582f4b9e86b6caa621cabeb0963332d92eea04729ab12892c2533951e6440"
+
 [[package]]
 name = "libc"
 version = "0.2.125"
@@ -122,6 +128,30 @@ dependencies = [
  "getopts",
  "log 0.3.9",
  "rand 0.3.23",
+ "serde_json",
+]
+
+[[package]]
+name = "ryu"
+version = "1.0.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7b4b9743ed687d4b4bcedf9ff5eaa7398495ae14e61cba0a295704edbc7decde"
+
+[[package]]
+name = "serde"
+version = "1.0.152"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bb7d1f0d3021d347a83e556fc4683dea2ea09d87bccdf88ff5c12545d89d5efb"
+
+[[package]]
+name = "serde_json"
+version = "1.0.91"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "877c235533714907a8c2464236f5c4b2a17262ef1bd71f38f35ea592c8da6883"
+dependencies = [
+ "itoa",
+ "ryu",
+ "serde",
 ]
 
 [[package]]
diff --git a/Cargo.toml b/Cargo.toml
index 3cf3cfb..dc3c7eb 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,3 +11,4 @@ getopts = "0.2.14"
 fnv = "1.0.0"
 float-ord = "0.2.0"
 crossbeam = "0.2.5"
+serde_json = "*"
diff --git a/src/game.rs b/src/game.rs
index 4e92989..fa1d56e 100644
--- a/src/game.rs
+++ b/src/game.rs
@@ -368,7 +368,9 @@ impl BoardState {
     }
 
     pub fn is_over(&self) -> bool {
-        (self.lives_remaining == 0) || (self.deckless_turns_remaining == 0)
+        (self.lives_remaining == 0)
+            || (self.deckless_turns_remaining == 0)
+            || (self.score() == PERFECT_SCORE)
     }
 }
 impl fmt::Display for BoardState {
@@ -522,12 +524,28 @@ impl GameView for OwnedGameView {
     }
 }
 
+// Internally, every card is annotated with its index in the deck in order to
+// generate easy-to-interpret JSON output. These annotations are stripped off
+// when passing GameViews to strategies.
+//
+// TODO: Maybe we should give strategies access to the annotations as well?
+// This could simplify code like in InformationPlayerStrategy::update_public_info_for_discard_or_play.
+// Also, this would let a strategy publish "notes" on cards more easily.
+pub type AnnotatedCard = (usize, Card);
+pub type AnnotatedCards = Vec<AnnotatedCard>;
+
+fn strip_annotations(cards: &AnnotatedCards) -> Cards {
+    cards.iter().map(|(_i, card)| card.clone()).collect()
+}
+
 // complete game state (known to nobody!)
 #[derive(Debug)]
 pub struct GameState {
-    pub hands: FnvHashMap<Player, Cards>,
+    pub hands: FnvHashMap<Player, AnnotatedCards>,
+    // used to construct BorrowedGameViews
+    pub unannotated_hands: FnvHashMap<Player, Cards>,
     pub board: BoardState,
-    pub deck: Cards,
+    pub deck: AnnotatedCards,
 }
 impl fmt::Display for GameState {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
@@ -538,7 +556,7 @@ impl fmt::Display for GameState {
         for player in self.board.get_players() {
             let hand = &self.hands.get(&player).unwrap();
             write!(f, "player {player}:")?;
-            for card in hand.iter() {
+            for (_i, card) in hand.iter() {
                 write!(f, "    {card}")?;
             }
             f.write_str("\n")?;
@@ -552,7 +570,9 @@ impl fmt::Display for GameState {
 }
 
 impl GameState {
-    pub fn new(opts: &GameOptions, mut deck: Cards) -> GameState {
+    pub fn new(opts: &GameOptions, deck: Cards) -> GameState {
+        // We enumerate the cards in reverse order since they'll be drawn from the back of the deck.
+        let mut deck: AnnotatedCards = deck.into_iter().rev().enumerate().rev().collect();
         let mut board = BoardState::new(opts, deck.len() as u32);
 
         let hands = (0..opts.num_players)
@@ -567,8 +587,17 @@ impl GameState {
                 (player, hand)
             })
             .collect::<FnvHashMap<_, _>>();
+        let unannotated_hands = hands
+            .iter()
+            .map(|(player, hand)| (*player, strip_annotations(hand)))
+            .collect::<FnvHashMap<_, _>>();
 
-        GameState { hands, board, deck }
+        GameState {
+            hands,
+            unannotated_hands,
+            board,
+            deck,
+        }
     }
 
     pub fn get_players(&self) -> Range<Player> {
@@ -586,7 +615,7 @@ impl GameState {
     // get the game state view of a particular player
     pub fn get_view(&self, player: Player) -> BorrowedGameView {
         let mut other_hands = FnvHashMap::default();
-        for (&other_player, hand) in &self.hands {
+        for (&other_player, hand) in &self.unannotated_hands {
             if player != other_player {
                 other_hands.insert(other_player, hand);
             }
@@ -599,10 +628,18 @@ impl GameState {
         }
     }
 
+    fn update_player_hand(&mut self) {
+        let player = self.board.player;
+        self.unannotated_hands
+            .insert(player, strip_annotations(self.hands.get(&player).unwrap()));
+    }
+
     // takes a card from the player's hand, and replaces it if possible
     fn take_from_hand(&mut self, index: usize) -> Card {
         let hand = &mut self.hands.get_mut(&self.board.player).unwrap();
-        hand.remove(index)
+        let card = hand.remove(index).1;
+        self.update_player_hand();
+        card
     }
 
     fn replenish_hand(&mut self) {
@@ -610,10 +647,11 @@ impl GameState {
         if (hand.len() as u32) < self.board.hand_size {
             if let Some(new_card) = self.deck.pop() {
                 self.board.deck_size -= 1;
-                debug!("Drew new card, {}", new_card);
+                debug!("Drew new card, {}", new_card.1);
                 hand.push(new_card);
             }
         }
+        self.update_player_hand();
     }
 
     pub fn process_choice(&mut self, choice: TurnChoice) -> TurnRecord {
@@ -637,11 +675,11 @@ impl GameState {
                     let results = match hint.hinted {
                         Hinted::Color(color) => hand
                             .iter()
-                            .map(|card| card.color == color)
+                            .map(|(_i, card)| card.color == color)
                             .collect::<Vec<_>>(),
                         Hinted::Value(value) => hand
                             .iter()
-                            .map(|card| card.value == value)
+                            .map(|(_i, card)| card.value == value)
                             .collect::<Vec<_>>(),
                     };
                     if !self.board.allow_empty_hints {
diff --git a/src/json_output.rs b/src/json_output.rs
new file mode 100644
index 0000000..4beb72f
--- /dev/null
+++ b/src/json_output.rs
@@ -0,0 +1,67 @@
+use crate::game::*;
+use serde_json::*;
+
+fn color_value(color: &Color) -> usize {
+    COLORS
+        .iter()
+        .position(|&card_color| &card_color == color)
+        .unwrap()
+}
+
+fn card_to_json(card: &Card) -> serde_json::Value {
+    json!({
+        "rank": card.value,
+        "suitIndex": color_value(&card.color),
+    })
+}
+
+pub fn action_clue(hint: &Hint) -> serde_json::Value {
+    match hint.hinted {
+        Hinted::Color(color) => {
+            json!({
+                "type": 2,
+                "target": hint.player,
+                "value": color_value(&color),
+            })
+        }
+        Hinted::Value(value) => {
+            json!({
+                "type": 3,
+                "target": hint.player,
+                "value": value,
+            })
+        }
+    }
+}
+
+pub fn action_play((i, _card): &AnnotatedCard) -> serde_json::Value {
+    json!({
+        "type": 0,
+        "target": i,
+    })
+}
+
+pub fn action_discard((i, _card): &AnnotatedCard) -> serde_json::Value {
+    json!({
+        "type": 1,
+        "target": i,
+    })
+}
+
+pub fn json_format(
+    deck: &Cards,
+    actions: &Vec<serde_json::Value>,
+    players: &Vec<String>,
+) -> serde_json::Value {
+    json!({
+        "options": {
+            "variant": "No Variant",
+        },
+        "players": players,
+        "first_player": 0,
+        "notes": players.iter().map(|_player| {json!([])}).collect::<Vec<_>>(), // TODO add notes
+        // The deck is reversed since in our implementation we draw from the end of the deck.
+        "deck": deck.iter().rev().map(card_to_json).collect::<Vec<serde_json::Value>>(),
+        "actions": actions,
+    })
+}
diff --git a/src/main.rs b/src/main.rs
index 3e8d538..8966662 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,9 +5,11 @@ extern crate crossbeam;
 extern crate float_ord;
 extern crate fnv;
 extern crate rand;
+extern crate serde_json;
 
 mod game;
 mod helpers;
+mod json_output;
 mod simulator;
 mod strategy;
 mod strategies {
@@ -60,6 +62,12 @@ fn main() {
         "Number of games after which to print an update",
         "OUTPUT_FREQ",
     );
+    opts.optopt(
+        "j",
+        "json-output",
+        "Pattern for the JSON output file. '%s' will be replaced by the seed.",
+        "FILE_PATTERN",
+    );
     opts.optopt(
         "t",
         "nthreads",
@@ -85,6 +93,11 @@ fn main() {
         "write-results-table",
         "Update the results table in README.md",
     );
+    opts.optflag(
+        "",
+        "losses-only",
+        "When saving JSON outputs, save lost games only",
+    );
     let matches = match opts.parse(&args[1..]) {
         Ok(m) => m,
         Err(f) => {
@@ -136,6 +149,8 @@ fn main() {
     let n_players = u32::from_str(matches.opt_str("p").as_deref().unwrap_or("4")).unwrap();
     let g_opt = matches.opt_str("g");
     let strategy_str: &str = g_opt.as_deref().unwrap_or("cheat");
+    let json_output_pattern = matches.opt_str("j");
+    let json_losses_only = matches.opt_present("losses-only");
 
     sim_games(
         n_players,
@@ -144,6 +159,8 @@ fn main() {
         n_trials,
         n_threads,
         progress_info,
+        json_output_pattern,
+        json_losses_only,
     )
     .info();
 }
@@ -155,6 +172,8 @@ fn sim_games(
     n_trials: u32,
     n_threads: u32,
     progress_info: Option<u32>,
+    json_output_pattern: Option<String>,
+    json_losses_only: bool,
 ) -> simulator::SimResult {
     let hand_size = match n_players {
         2 => 5,
@@ -195,6 +214,8 @@ fn sim_games(
         n_trials,
         n_threads,
         progress_info,
+        json_output_pattern,
+        json_losses_only,
     )
 }
 
@@ -250,8 +271,16 @@ fn get_results_table() -> String {
                 &player_nums,
                 (format_name(strategy), space.clone()),
                 &|n_players| {
-                    let simresult =
-                        sim_games(n_players, strategy, Some(seed), n_trials, n_threads, None);
+                    let simresult = sim_games(
+                        n_players,
+                        strategy,
+                        Some(seed),
+                        n_trials,
+                        n_threads,
+                        None,
+                        None,
+                        false,
+                    );
                     (
                         format_score(simresult.average_score(), simresult.score_stderr()),
                         format_percent(
diff --git a/src/simulator.rs b/src/simulator.rs
index 71ffc11..3467ef5 100644
--- a/src/simulator.rs
+++ b/src/simulator.rs
@@ -3,6 +3,7 @@ use rand::{self, Rng, SeedableRng};
 use std::fmt;
 
 use crate::game::*;
+use crate::json_output::*;
 use crate::strategy::*;
 
 fn new_deck(seed: u32) -> Cards {
@@ -25,10 +26,11 @@ pub fn simulate_once(
     opts: &GameOptions,
     game_strategy: Box<dyn GameStrategy>,
     seed: u32,
-) -> GameState {
+    output_json: bool,
+) -> (GameState, Option<serde_json::Value>) {
     let deck = new_deck(seed);
 
-    let mut game = GameState::new(opts, deck);
+    let mut game = GameState::new(opts, deck.clone());
 
     let mut strategies = game
         .get_players()
@@ -40,6 +42,8 @@ pub fn simulate_once(
         })
         .collect::<FnvHashMap<Player, Box<dyn PlayerStrategy>>>();
 
+    let mut actions = Vec::new();
+
     while !game.is_over() {
         let player = game.board.player;
 
@@ -53,6 +57,19 @@ pub fn simulate_once(
             let strategy = strategies.get_mut(&player).unwrap();
             strategy.decide(&game.get_view(player))
         };
+        if output_json {
+            actions.push(match choice {
+                TurnChoice::Hint(ref hint) => action_clue(hint),
+                TurnChoice::Play(index) => {
+                    let card = &game.hands[&player][index];
+                    action_play(card)
+                }
+                TurnChoice::Discard(index) => {
+                    let card = &game.hands[&player][index];
+                    action_discard(card)
+                }
+            });
+        }
 
         let turn = game.process_choice(choice);
 
@@ -65,7 +82,16 @@ pub fn simulate_once(
     debug!("=======================================================");
     debug!("Final state:\n{}", game);
     debug!("SCORE: {:?}", game.score());
-    game
+    let json_output = if output_json {
+        let player_names = game
+            .get_players()
+            .map(|player| strategies[&player].name())
+            .collect();
+        Some(json_format(&deck, &actions, &player_names))
+    } else {
+        None
+    };
+    (game, json_output)
 }
 
 #[derive(Debug)]
@@ -135,6 +161,8 @@ pub fn simulate<T: ?Sized>(
     n_trials: u32,
     n_threads: u32,
     progress_info: Option<u32>,
+    json_output_pattern: Option<String>,
+    json_losses_only: bool,
 ) -> SimResult
 where
     T: GameStrategyConfig + Sync,
@@ -142,6 +170,7 @@ where
     let first_seed = first_seed_opt.unwrap_or_else(|| rand::thread_rng().next_u32());
 
     let strat_config_ref = &strat_config;
+    let json_output_pattern_ref = &json_output_pattern;
     crossbeam::scope(|scope| {
         let mut join_handles = Vec::new();
         for i in 0..n_threads {
@@ -169,13 +198,27 @@ where
                             );
                         }
                     }
-                    let game = simulate_once(opts, strat_config_ref.initialize(opts), seed);
+                    let (game, json_output) = simulate_once(
+                        opts,
+                        strat_config_ref.initialize(opts),
+                        seed,
+                        json_output_pattern_ref.is_some(),
+                    );
                     let score = game.score();
                     lives_histogram.insert(game.board.lives_remaining);
                     score_histogram.insert(score);
                     if score != PERFECT_SCORE {
                         non_perfect_seeds.push(seed);
                     }
+                    if let Some(file_pattern) = json_output_pattern_ref {
+                        if !(score == PERFECT_SCORE && json_losses_only) {
+                            let file_pattern =
+                                file_pattern.clone().replace("%s", &seed.to_string());
+                            let path = std::path::Path::new(&file_pattern);
+                            let file = std::fs::File::create(path).unwrap();
+                            serde_json::to_writer(file, &json_output.unwrap()).unwrap();
+                        }
+                    }
                 }
                 if progress_info.is_some() {
                     info!("Thread {} done", i);
diff --git a/src/strategies/cheating.rs b/src/strategies/cheating.rs
index fd9bc94..38c9118 100644
--- a/src/strategies/cheating.rs
+++ b/src/strategies/cheating.rs
@@ -136,6 +136,9 @@ impl CheatingPlayerStrategy {
     }
 }
 impl PlayerStrategy for CheatingPlayerStrategy {
+    fn name(&self) -> String {
+        String::from("cheat")
+    }
     fn decide(&mut self, view: &BorrowedGameView) -> TurnChoice {
         self.inform_last_player_cards(view);
 
diff --git a/src/strategies/examples.rs b/src/strategies/examples.rs
index 6f3f3eb..1a65f28 100644
--- a/src/strategies/examples.rs
+++ b/src/strategies/examples.rs
@@ -39,6 +39,12 @@ pub struct RandomStrategyPlayer {
 }
 
 impl PlayerStrategy for RandomStrategyPlayer {
+    fn name(&self) -> String {
+        format!(
+            "random(hint={}, play={})",
+            self.hint_probability, self.play_probability
+        )
+    }
     fn decide(&mut self, view: &BorrowedGameView) -> TurnChoice {
         let p = rand::random::<f64>();
         if p < self.play_probability {
diff --git a/src/strategies/information.rs b/src/strategies/information.rs
index 8a98b33..e8da327 100644
--- a/src/strategies/information.rs
+++ b/src/strategies/information.rs
@@ -991,6 +991,10 @@ impl InformationPlayerStrategy {
 }
 
 impl PlayerStrategy for InformationPlayerStrategy {
+    fn name(&self) -> String {
+        String::from("info")
+    }
+
     fn decide(&mut self, _: &BorrowedGameView) -> TurnChoice {
         let mut public_info = self.public_info.clone();
         let turn_choice = self.decide_wrapped(&mut public_info);
diff --git a/src/strategy.rs b/src/strategy.rs
index 5b83f58..2e370f3 100644
--- a/src/strategy.rs
+++ b/src/strategy.rs
@@ -4,6 +4,11 @@ use crate::game::*;
 
 // Represents the strategy of a given player
 pub trait PlayerStrategy {
+    // A function returning the name of a strategy.
+    // This is a method of PlayerStrategy rather than GameStrategyConfig
+    // so that the name may incorporate useful information that's specific
+    // to this player instance.
+    fn name(&self) -> String;
     // A function to decide what to do on the player's turn.
     // Given a BorrowedGameView, outputs their choice.
     fn decide(&mut self, view: &BorrowedGameView) -> TurnChoice;