diff --git a/src/main/java/com/alttd/hunger_games/Main.java b/src/main/java/com/alttd/hunger_games/Main.java
index 1418ff4..eabaed3 100644
--- a/src/main/java/com/alttd/hunger_games/Main.java
+++ b/src/main/java/com/alttd/hunger_games/Main.java
@@ -3,6 +3,7 @@ package com.alttd.hunger_games;
 import com.alttd.hunger_games.commands.BaseCommand;
 import com.alttd.hunger_games.config.Config;
 import com.alttd.hunger_games.config.Messages;
+import com.alttd.hunger_games.services.PlayerService;
 import com.alttd.hunger_games.services.Round;
 import com.alttd.hunger_games.services.RoundService;
 import lombok.extern.slf4j.Slf4j;
@@ -12,9 +13,8 @@ import org.bukkit.plugin.java.JavaPlugin;
 @Slf4j
 public final class Main extends JavaPlugin {
 
-    private BaseCommand command;
-    private Round round;
     private RoundService roundService;
+    private PlayerService playerService;
 
     @Override
     public void onEnable() {
@@ -27,8 +27,9 @@ public final class Main extends JavaPlugin {
     }
 
     private void registerServices() {
-        round = Round.createSingletonInstance();
+        Round round = Round.createSingletonInstance();
         roundService = new RoundService(round);
+        playerService = new PlayerService(roundService);
     }
 
     @Override
@@ -37,7 +38,7 @@ public final class Main extends JavaPlugin {
     }
 
     private void registerCommands() {
-        command = new BaseCommand(this, roundService);
+        BaseCommand command = new BaseCommand(this, roundService, playerService);
     }
 
     private void registerEvents() {
diff --git a/src/main/java/com/alttd/hunger_games/commands/BaseCommand.java b/src/main/java/com/alttd/hunger_games/commands/BaseCommand.java
index 3a99082..529a75e 100644
--- a/src/main/java/com/alttd/hunger_games/commands/BaseCommand.java
+++ b/src/main/java/com/alttd/hunger_games/commands/BaseCommand.java
@@ -1,8 +1,10 @@
 package com.alttd.hunger_games.commands;
 
 import com.alttd.hunger_games.Main;
+import com.alttd.hunger_games.commands.subcommands.Register;
 import com.alttd.hunger_games.commands.subcommands.RoundState;
 import com.alttd.hunger_games.config.Messages;
+import com.alttd.hunger_games.services.PlayerService;
 import com.alttd.hunger_games.services.RoundService;
 import lombok.Getter;
 import lombok.extern.slf4j.Slf4j;
@@ -19,7 +21,7 @@ import java.util.stream.Collectors;
 public class BaseCommand implements CommandExecutor, TabExecutor {
     private final List<SubCommand> subCommands;
 
-    public BaseCommand(Main main, RoundService roundService) {
+    public BaseCommand(Main main, RoundService roundService, PlayerService playerService) {
         PluginCommand command = main.getCommand("hungergames");
         if (command == null) {
             subCommands = null;
@@ -31,8 +33,9 @@ public class BaseCommand implements CommandExecutor, TabExecutor {
         command.setAliases(List.of("hg"));
 
         subCommands = new ArrayList<>(List.of(
-                new RoundState(roundService)
-                                             ));
+                new RoundState(roundService),
+                new Register(playerService)
+                                              ));
     }
 
     @Override
diff --git a/src/main/java/com/alttd/hunger_games/commands/subcommands/Register.java b/src/main/java/com/alttd/hunger_games/commands/subcommands/Register.java
new file mode 100644
index 0000000..891a286
--- /dev/null
+++ b/src/main/java/com/alttd/hunger_games/commands/subcommands/Register.java
@@ -0,0 +1,110 @@
+package com.alttd.hunger_games.commands.subcommands;
+
+import com.alttd.hunger_games.commands.SubCommand;
+import com.alttd.hunger_games.commands.shared_parsers.OnlinePlayerParser;
+import com.alttd.hunger_games.config.Messages;
+import com.alttd.hunger_games.data_objects.PLAYER_STATE;
+import com.alttd.hunger_games.services.PlayerService;
+import lombok.extern.slf4j.Slf4j;
+import net.kyori.adventure.text.minimessage.tag.resolver.Placeholder;
+import org.bukkit.command.CommandSender;
+import org.bukkit.entity.Player;
+
+import javax.annotation.Nullable;
+import java.util.List;
+import java.util.Optional;
+
+@Slf4j
+public class Register extends SubCommand {
+
+    private final static OnlinePlayerParser ONLINE_PLAYER_PARSER = new OnlinePlayerParser();
+    private final static int PLAYER_ARG = 1;
+    private final PlayerService playerService;
+
+    public Register(PlayerService playerService) {
+        this.playerService = playerService;
+    }
+
+    @Override
+    public boolean onCommand(CommandSender commandSender, String[] args) {
+        if (args.length != 2) {
+            return false;
+        }
+
+        Optional<Player> optionalPlayer = ONLINE_PLAYER_PARSER.parse(commandSender, args[PLAYER_ARG]);
+        if (optionalPlayer.isEmpty()) {
+            return true;
+        }
+
+        Player playerToRegister = optionalPlayer.get();
+        Optional<PLAYER_STATE> optionalPlayerState = playerService.registerPlayer(playerToRegister);
+        PLAYER_STATE nullablePlayerState = optionalPlayerState.orElse(null);
+        if (optionalPlayerState.isEmpty()) {
+            playerToRegister.sendRichMessage(Messages.REGISTER.FAILED_TO_REGISTER_YOU);
+        } else {
+            notifyRegisteredPlayer(playerToRegister, nullablePlayerState);
+        }
+
+        if (commandSender instanceof Player commandPlayer) {
+            notifyPlayerCommandSender(commandPlayer, nullablePlayerState, playerToRegister);
+        }
+        logResult(nullablePlayerState, playerToRegister);
+        return true;
+    }
+
+    private void notifyRegisteredPlayer(Player playerToRegister, PLAYER_STATE nullablePlayerState) {
+        switch (nullablePlayerState) {
+            case REGISTERED -> playerToRegister.sendRichMessage(Messages.REGISTER.SUCCESSFUL_REGISTER);
+            case SPECTATING -> playerToRegister.sendRichMessage(Messages.REGISTER.GAME_RUNNING);
+        }
+    }
+
+    private void logResult(PLAYER_STATE nullablePlayerState, Player playerToRegister) {
+        if (nullablePlayerState == null) {
+            log.info("Failed to register player {}", playerToRegister.getName());
+            return;
+        }
+
+        switch (nullablePlayerState) {
+            case REGISTERED -> log.info("Registered player {} for the next round", playerToRegister.getName());
+            case IN_GAME -> log.info("Player {} is already in a round", playerToRegister.getName());
+            case DISCONNECTED -> log.info("Player {} is disconnected (should not be possible)", playerToRegister.getName());
+            case SPECTATING -> log.info("Player {} is now spectating the game", playerToRegister.getName());
+        }
+    }
+
+    private static void notifyPlayerCommandSender(Player commandPlayer, @Nullable PLAYER_STATE playerState, Player playerToRegister) {
+        if (playerState == null) {
+            commandPlayer.sendRichMessage(Messages.REGISTER.FAILED_TO_REGISTER_PLAYER,
+                    Placeholder.component("player", playerToRegister.name()));
+            return;
+        }
+
+        switch (playerState) {
+            case REGISTERED -> commandPlayer.sendRichMessage(Messages.REGISTER.PLAYER_REGISTERED,
+                                                            Placeholder.component("player", playerToRegister.name()));
+            case IN_GAME -> commandPlayer.sendRichMessage(Messages.REGISTER.PLAYER_ALREADY_IN_ROUND,
+                                                      Placeholder.component("player", playerToRegister.name()));
+            case DISCONNECTED -> {
+                //should not be possible
+            }
+            case SPECTATING -> commandPlayer.sendRichMessage(Messages.REGISTER.PLAYER_SPECTATING,
+                                                         Placeholder.component("player", playerToRegister.name()));
+        }
+    }
+
+    @Override
+    public String getName() {
+        return "register";
+    }
+
+    @Override
+    public List<String> getTabComplete(CommandSender commandSender, String[] args) {
+        return List.of();
+    }
+
+    @Override
+    public String getHelpMessage() {
+        return Messages.HELP.REGISTER;
+    }
+}
diff --git a/src/main/java/com/alttd/hunger_games/config/Messages.java b/src/main/java/com/alttd/hunger_games/config/Messages.java
index 39823ce..6c7489b 100644
--- a/src/main/java/com/alttd/hunger_games/config/Messages.java
+++ b/src/main/java/com/alttd/hunger_games/config/Messages.java
@@ -69,11 +69,21 @@ public class Messages extends AbstractConfig {
 
         public static String FAILED_TO_REGISTER_YOU = "<red>You were unable to join HungerGames because no HungerGames round was found</red>";
         public static String FAILED_TO_REGISTER_PLAYER = "<red>Unable to register player <player></red>";
+        public static String PLAYER_REGISTERED = "<green>Registered <player> for the game</green>";
+        public static String PLAYER_ALREADY_IN_ROUND = "<yellow><player> is already in a round</yellow>";
+        public static String PLAYER_SPECTATING = "<yellow><player> is now spectating the game</yellow>";
+        public static String SUCCESSFUL_REGISTER = "<green>Successfully registered you for the upcoming Hunger Games round</green>";
+        public static String GAME_RUNNING = "<yellow>The game is currently running, you will need to spectate the current round</yellow>";
 
         @SuppressWarnings("unused")
         private static void load() {
             FAILED_TO_REGISTER_YOU = config.getString(prefix, "failed", FAILED_TO_REGISTER_YOU);
             FAILED_TO_REGISTER_PLAYER = config.getString(prefix, "failed-player", FAILED_TO_REGISTER_PLAYER);
+            PLAYER_REGISTERED = config.getString(prefix, "player-registered", PLAYER_REGISTERED);
+            PLAYER_ALREADY_IN_ROUND = config.getString(prefix, "player-already-in-game", PLAYER_ALREADY_IN_ROUND);
+            PLAYER_SPECTATING = config.getString(prefix, "player-spectating", PLAYER_SPECTATING);
+            SUCCESSFUL_REGISTER = config.getString(prefix, "successful", SUCCESSFUL_REGISTER);
+            GAME_RUNNING = config.getString(prefix, "game-running", GAME_RUNNING);
         }
     }
 }
diff --git a/src/main/java/com/alttd/hunger_games/services/PlayerService.java b/src/main/java/com/alttd/hunger_games/services/PlayerService.java
index 45043c0..85f4bcb 100644
--- a/src/main/java/com/alttd/hunger_games/services/PlayerService.java
+++ b/src/main/java/com/alttd/hunger_games/services/PlayerService.java
@@ -3,9 +3,10 @@ package com.alttd.hunger_games.services;
 import com.alttd.hunger_games.data_objects.PLAYER_STATE;
 import com.alttd.hunger_games.data_objects.ROUND_STATE;
 import lombok.RequiredArgsConstructor;
+import org.bukkit.Bukkit;
 import org.bukkit.entity.Player;
 
-import java.util.Optional;
+import java.util.*;
 
 @RequiredArgsConstructor
 public class PlayerService implements RoundListener {
@@ -16,29 +17,70 @@ public class PlayerService implements RoundListener {
     @Override
     public void stateChange(ROUND_STATE roundState) {
         this.roundState = roundState;
-        //TODO: Implement player state change logic
+        switch (roundState) {
+            case PLAYER_REGISTRATION, KILL_PHASE -> {
+                //Nothing
+            }
+            case COUNTDOWN -> {
+                setNonRegisteredPlayersToSpectator();
+                //TODO: teleport players to spawn location
+            }
+            case FINALE -> {
+                //TODO: teleport players to finale location
+            }
+            case ENDED -> {
+                roundService.clear();
+                //TODO: teleport everyone to spawn (or spectator?) location
+            }
+        }
+    }
+
+    private void setNonRegisteredPlayersToSpectator() {
+        Set<UUID> playerUUIDs = roundService.getPlayers(PLAYER_STATE.REGISTERED);
+        List<Player> playerList = new ArrayList<>(Bukkit.getOnlinePlayers());
+        List<Player> unregisteredPlayers = playerList.stream().filter(player -> !playerUUIDs.contains(player.getUniqueId())).toList();
+        unregisteredPlayers.forEach(player -> roundService.setPlayerState(player.getUniqueId(), PLAYER_STATE.SPECTATING));
     }
 
     @Override
     public void roundReset() {
-        //TODO: Implement player reset logic
+        //TODO: teleport everyone to spawn (or spectator?) location (from where they can join the game)
     }
 
     public Optional<PLAYER_STATE> registerPlayer(Player player) {
         if (roundState == null) {
             return Optional.empty();
         }
-        switch (roundState) {
-            case PLAYER_REGISTRATION -> {
-            }
-            case COUNTDOWN -> {
-            }
-            case KILL_PHASE -> {
-            }
-            case FINALE -> {
-            }
-            case ENDED -> {
-            }
+        Optional<PLAYER_STATE> optionalPlayerState = determinePlayerState(player.getUniqueId());
+        if (optionalPlayerState.isEmpty()) {
+            return Optional.empty();
         }
+        PLAYER_STATE playerState = optionalPlayerState.get();
+
+        if (playerState == PLAYER_STATE.SPECTATING) {
+            //TODO: teleport player to spectator location
+        }
+
+        roundService.setPlayerState(player.getUniqueId(), playerState);
+        return optionalPlayerState;
+    }
+
+    private Optional<PLAYER_STATE> determinePlayerState(UUID playerUuid) {
+        if (roundState == null) {
+            return Optional.empty();
+        }
+        Optional<PLAYER_STATE> optionalPlayerState = roundService.getPlayerState(playerUuid);
+        if (optionalPlayerState.isPresent()) {
+            PLAYER_STATE playerState = optionalPlayerState.get();
+            return Optional.of(switch (playerState) {
+                case DISCONNECTED, SPECTATING -> PLAYER_STATE.SPECTATING;
+                case IN_GAME -> PLAYER_STATE.IN_GAME;
+                case REGISTERED -> PLAYER_STATE.REGISTERED;
+            });
+        }
+        return switch (roundState) {
+            case PLAYER_REGISTRATION, COUNTDOWN -> Optional.of(PLAYER_STATE.REGISTERED);
+            case KILL_PHASE, FINALE, ENDED -> Optional.of(PLAYER_STATE.SPECTATING);
+        };
     }
 }
diff --git a/src/main/java/com/alttd/hunger_games/services/RoundService.java b/src/main/java/com/alttd/hunger_games/services/RoundService.java
index a2addef..c4f499e 100644
--- a/src/main/java/com/alttd/hunger_games/services/RoundService.java
+++ b/src/main/java/com/alttd/hunger_games/services/RoundService.java
@@ -5,10 +5,7 @@ import com.alttd.hunger_games.data_objects.ROUND_STATE;
 import lombok.Getter;
 import org.bukkit.entity.Player;
 
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Set;
-import java.util.UUID;
+import java.util.*;
 import java.util.stream.Collectors;
 
 public class RoundService implements RoundListener {
@@ -32,8 +29,12 @@ public class RoundService implements RoundListener {
         players.put(uuid, playerState);
     }
 
-    public PLAYER_STATE getPlayerState(UUID uuid) {
-        return players.get(uuid);
+    protected void clear() {
+        players.clear();
+    }
+
+    public Optional<PLAYER_STATE> getPlayerState(UUID uuid) {
+        return Optional.ofNullable(players.get(uuid));
     }
 
     @Override
@@ -43,7 +44,7 @@ public class RoundService implements RoundListener {
 
     @Override
     public void roundReset() {
-        players.clear();
+        clear();
         roundState = null;
     }
 }