Just got it…

def check_connection
  recv # receive packets

  case @state
  when STATE_NOT_CONNECTED
    reconnect
  when STATE_CONNECTED_TO_LOGIN
    @packets.pop do |packet|
      case packet
      when Com::AnkamaGames::Dofus::Network::Messages::Handshake::ProtocolRequired
        if packet.requiredVersion > $config.protocol_build
          log("Current protocol build: #{$config.protocol_build}, required build: #{packet.requiredVersion}", Logger::FATAL)
        end

        if packet.currentVersion < $config.protocol_required_build
          log("Current protocol build: #{$config.protocol_required_build}, is too new for the server version: #{packet.currentVersion}", Logger::FATAL)
        end
      when HelloConnectMessage
        $config.session_key = packet.sessionKey

        im = IdentificationMessage.new
        bytes = im.build!({
          username: $config.username,
          password: $config.password,
          version: $config.version,
          session_key: $config.session_key
        })

        send_data bytes
      when Com::AnkamaGames::Dofus::Network::Messages::Queues::LoginQueueStatusMessage
        l("Position in login queue: #{packet.position} / #{packet.total}")
      when IdentificationSuccessMessage
        l('Authentification successful', Logger::OK)
        @state = STATE_SERVERS_LIST
      else
        l("Incorrect packet at $net.STATE_CONNECTED_TO_LOGIN: #{packet.class}", Logger::FATAL)
      end
    end
  when STATE_SERVERS_LIST
    @packets.pop do |packet|
      case packet
      when ServersListMessage
        if !$config.server_id
          "Select server:".to_block(10) {
            packet.servers.select { |s| s.status == s.class::STATUS_ONLINE }.each do |s|
              printf("%5d %s %d %s\n", s.id, "-", s.charactersCount, s.status_t)
            end
          }

          while line = gets do
            line.strip!
            next if line.empty?

            exit if line.to_i == 0

            server = packet.servers.find { |s| s.id == line.to_i }
            next unless server

            $config.server_id = server.id
            break
          end
        end

        ssm = ServerSelectionMessage.new.build!($config.server_id)
        send_data ssm
      when SelectedServerDataMessage
        @ip = packet.address
        @port = packet.port
        $config.ticket = packet.ticket

        reconnect

        @state = STATE_CONNECTED_TO_GAME
      else
        l("Incorrect packet at $net.STATE_SERVERS_LIST: #{packet.class}", Logger::FATAL)
      end
    end
  when STATE_CONNECTED_TO_GAME
    @packets.pop do |packet|
      case packet
      when Com::AnkamaGames::Dofus::Network::Messages::Handshake::ProtocolRequired
        if packet.requiredVersion > $config.protocol_build
          log("Current protocol build: #{$config.protocol_build}, required build: #{packet.requiredVersion}", Logger::FATAL)
        end

        if packet.currentVersion < $config.protocol_required_build
          log("Current protocol build: #{$config.protocol_required_build}, is too new for the server version: #{packet.currentVersion}", Logger::FATAL)
        end
      when HelloGameMessage
        atm = AuthenticationTicketMessage.new.build!('en', $config.ticket)
        send_data atm
      when AuthenticationTicketAcceptedMessage
        l("Ticket accepted", Logger::OK)
      when Com::AnkamaGames::Dofus::Network::Messages::Game::Basic::BasicTimeMessage
        # nothing to do, just ignore
      when Com::AnkamaGames::Dofus::Network::Messages::Game::Approach::AccountCapabilitiesMessage
        $config.account_id = packet.account_id

        clrm = Com::AnkamaGames::Dofus::Network::Messages::Game::Character::Choice::CharactersListRequestMessage.new.build!
        send_data clrm

        @state = STATE_CHARACTER_SELECTION
      else
        l("Incorrect packet at $net.STATE_CONNECTED_TO_GAME: #{packet.class}", Logger::FATAL)
      end
    end
  when STATE_CHARACTER_SELECTION
    @packets.pop do |packet|
      case packet
      when Com::AnkamaGames::Dofus::Network::Messages::Queues::QueueStatusMessage
        l("Position in character selection queue: #{packet.position} / #{packet.total}")
      when Com::AnkamaGames::Dofus::Network::Messages::Secure::TrustStatusMessage,
           Com::AnkamaGames::Dofus::Network::Messages::Game::Basic::BasicNoOperationMessage
        # nothing to do, ignore
      when Com::AnkamaGames::Dofus::Network::Messages::Game::Character::Choice::CharactersListMessage
        characters = packet.characters

        if !$config.character_id && characters.size > 0
          puts "Choose your character:"

          fields = sprintf("%20s | %5s | %5s | %6s", 'Name', 'Level', 'Class', 'Sex')
          puts fields, '-' * fields.size

          characters.each do |c|
            puts sprintf("%20s | %5d | %5d | %6s", c.name, c.level, c.breed, c.sex ? 'Male' : 'Female')
          end

          while line = gets do
            line.strip!
            break if line.empty?

            character = characters.find { |c| c.name.downcase == line.downcase }
            next unless character

            $config.character_id = character.id
            break
          end

          csm = Com::AnkamaGames::Dofus::Network::Messages::Game::Character::Choice::CharacterSelectionMessage.new.build!($config.character_id)
          send_data csm

          @state = STATE_IN_GAME
        elsif characters.size == 0
          l("No character created", Logger::FATAL)
          exit
        end
      else
        l("Incorrect packet at $net.STATE_CHARACTER_SELECTION: #{packet.class}", Logger::FATAL)
      end
    end
  when STATE_IN_GAME
  else
    l("Unknown state #{state} for $net", Logger::FATAL);
    exit
  end
end

Output

[user host-122 ~/Documents/Projects/dofus] ./run.rb
[ INFO] [D2O] Parsing Servers.d2o
[ INFO] Connected
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Handshake::ProtocolRequired
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Connection::HelloConnectMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Connection::IdentificationMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Connection::IdentificationSuccessMessage
[   OK] Authentification successful
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Connection::ServersListMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Connection::ServerSelectionMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Connection::SelectedServerDataMessage
[ INFO] Connected
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Handshake::ProtocolRequired
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Approach::HelloGameMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Approach::AuthenticationTicketMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Approach::AuthenticationTicketAcceptedMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Basic::BasicTimeMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Approach::AccountCapabilitiesMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Secure::TrustStatusMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Basic::BasicNoOperationMessage
[   OK] Ticket accepted
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Character::Choice::CharactersListRequestMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Queues::QueueStatusMessage
[ INFO] Position in character selection queue: 1 / 1
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Queues::QueueStatusMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Basic::BasicNoOperationMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Queues::QueueStatusMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Character::Choice::CharactersListMessage
[ INFO] Position in character selection queue: 0 / 0
[ INFO] Position in character selection queue: 0 / 0
Choose your character:
                Name | Level | Class |    Sex
---------------------------------------------
               Char1 |     2 |     5 |   Male
               Char2 |     4 |     3 | Female
               Char3 |    19 |     9 | Female
Char1
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Character::Choice::CharacterSelectionMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Basic::BasicNoOperationMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Context::Notification::NotificationListMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Character::Choice::CharacterSelectedSuccessMessage
[ INFO] Selected character: [------] Char1 (2)
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Inventory::Items::InventoryContentMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Inventory::Items::SetUpdateMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Shortcut::ShortcutBarContentMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Shortcut::ShortcutBarContentMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Context::Roleplay::Emote::EmoteListMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Pvp::AlignmentRankUpdateMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Pvp::AlignmentSubAreasListMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Chat::Channel::EnabledChannelsMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Inventory::Spells::SpellListMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Shortcut::ShortcutBarContentMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Initialization::SetCharacterRestrictionsMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Inventory::Items::InventoryWeightMessage
[ INFO] Character weight: 14 / 1000
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Friend::FriendWarnOnConnectionStateMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Friend::GuildMemberWarnOnConnectionStateMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Friend::FriendWarnOnLevelGainStateMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Basic::TextInformationMessage
[ WARN] Check Com::AnkamaGames::Dofus::Network::Messages::Game::Basic::TextInformationMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Basic::TextInformationMessage
[ WARN] Check Com::AnkamaGames::Dofus::Network::Messages::Game::Basic::TextInformationMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Initialization::ServerExperienceModificatorMessage
[DEBUG] Com::AnkamaGames::Dofus::Network::Messages::Game::Friend::SpouseStatusMessage

P.S. Please don’t blame my ugly code :)