diff --git a/src/cligen/app.cr b/src/cligen/app.cr
index 35446e1..8a52bec 100644
--- a/src/cligen/app.cr
+++ b/src/cligen/app.cr
@@ -14,11 +14,8 @@ module CliGen
       @@instance = self
     end
 
-    def check! : Nil
-      CliGen::GLOBAL_FLAGS.each(&.check!)
-      # @flags is the amalgamation of all child flags — checked by the commands themselves
-      check_for_duplicates!([CliGen::GLOBAL_FLAGS, @flags].flatten)
-      @commands.each(&.check!)
+    def check!
+      super
     end
 
     # Convenience entry point; defaults to ARGV
diff --git a/src/cligen/app/generate.cr b/src/cligen/app/generate.cr
index 73c42f0..df1691b 100644
--- a/src/cligen/app/generate.cr
+++ b/src/cligen/app/generate.cr
@@ -30,7 +30,7 @@ module CliGen
               validate: {% if anno[:validation] %} {{anno[:validation]}} {% else %} nil {% end %},
               on_match: {% if anno[:on_match] %} {{anno[:on_match]}} {% else %} nil {% end %},
               options: {% if anno[:options] %} {{anno[:options]}} {% else %} nil {% end %},
-              delimiter: {% if anno[:delimiter] %} {{anno[:delimiter]}} {% else %} nil {% end %},
+              delimiter: {% if anno[:delimiter] %} {{anno[:delimiter]}} {% else %} "," {% end %},
               format: {% if anno[:format] %} {{anno[:format]}} {% else %} nil {% end %}
             )
           {% debug if env("DEBUG") %}
diff --git a/src/cligen/command.cr b/src/cligen/command.cr
index f5fc097..751906b 100644
--- a/src/cligen/command.cr
+++ b/src/cligen/command.cr
@@ -7,6 +7,7 @@ require "./command/selection"
 require "./command/help_template"
 require "./command/subcommand"
 require "./command/def_init"
+require "./command/define_command_initializer"
 
 module CliGen
   class Command
@@ -18,28 +19,7 @@ module CliGen
         {% if anno[:def_init] %}
           def_init
         {% end %}
-        def initialize(*, handler : CliGen::BaseCommandNode)
-          {% verbatim do %}
-            {% for var in @type.instance_vars %}
-              {% anno = (var.annotation(CliGen::Argument) || var.annotation(CliGen::Selection)) %}
-              {% if anno %}
-                {% raise "ERROR : #{@type.name}#initialize : Argument '#{var.name}' cannot be a nilable type (#{var.type}) — flags always resolve to a concrete value" if var.type.union? %}
-                if flg = handler.flags.find{|f| f.var == {{var.name.stringify}} && f.long == {{anno[:long]}}}
-                  @{{var.id}} = flg.as(CliGen::Flag({{var.type}})).value!
-                else
-                  raise "ERROR : {{@type.name}}\#{{@def.name}} : No flag found for \"{{var.name}}\"?"
-                end
-              {% else %}
-                {% raise "ERROR : #{@type.name}#{@def.name} : Instance Variable(#{var.name}) is not handled by CliGen and does not have a default value" unless var.default_value %}
-                @{{var.id}} = {{var.default_value}}
-              {% end %}
-            {% end %}
-
-            {% if @type.has_method? :after_initialize %}
-              after_initialize
-            {% end %}
-          {% end %}
-        end
+        define_command_initializer
       end
       {% end %}
     end
diff --git a/src/cligen/command/argument.cr b/src/cligen/command/argument.cr
index c3f88eb..43252db 100644
--- a/src/cligen/command/argument.cr
+++ b/src/cligen/command/argument.cr
@@ -44,11 +44,17 @@ module CliGen
       {% if type.resolve <= Array && format.nil? %}
         {% elem = type.type_vars.first %}
         {% unless elem == Int32 %}
-          {% raise "ERROR : CliGen::Command.argument(#{name}) : When providing custom data types for Array(T) or using Array(String) you must provide a format for argument filtering so that parsing can be done deterministically" %}
+          {% if format.nil? && options.nil? %}
+            {% raise "ERROR : CliGen::Command.argument(#{name}) : When providing custom data types for Array(T) or using Array(String) you must provide a format or options for argument filtering so that parsing can be done deterministically" %}
+          {% end %}
         {% end %}
       {% end %}
 
+      {% if type.resolve < Array && ! options.nil? %}
+      @[CliGen::Argument(short: {{short}}, long: {{long}}, description: {{description}}, validation: {{validation}}, on_match: {{on_match}}, options: [{{options}}], delimiter: {{delimiter}}, format: {{format}})]
+      {% else %}
       @[CliGen::Argument(short: {{short}}, long: {{long}}, description: {{description}}, validation: {{validation}}, on_match: {{on_match}}, options: {{options}}, delimiter: {{delimiter}}, format: {{format}})]
+      {% end %}
       @{{variable}}
 
       {% if def_getter %}
diff --git a/src/cligen/command/define_command_initializer.cr b/src/cligen/command/define_command_initializer.cr
new file mode 100644
index 0000000..87f7d43
--- /dev/null
+++ b/src/cligen/command/define_command_initializer.cr
@@ -0,0 +1,29 @@
+module CliGen
+  class Command
+    macro define_command_initializer
+      def initialize(*, handler : CliGen::BaseCommandNode)
+        {% verbatim do %}
+          {% for var in @type.instance_vars %}
+            {% anno = (var.annotation(CliGen::Argument) || var.annotation(CliGen::Selection)) %}
+            {% if anno %}
+              {% raise "ERROR : #{@type.name}#initialize : Argument '#{var.name}' cannot be a nilable type (#{var.type}) — flags always resolve to a concrete value" if var.type.union? %}
+              if flg = handler.flags.find{|f| f.var == {{var.name.stringify}} && f.long == {{anno[:long]}}}
+                flg.validate!
+                @{{var.id}} = flg.as(CliGen::Flag({{var.type}})).value!
+              else
+                raise "ERROR : {{@type.name}}\#{{@def.name}} : No flag found for \"{{var.name}}\"?"
+              end
+            {% else %}
+              {% raise "ERROR : #{@type.name}#{@def.name} : Instance Variable(#{var.name}) is not handled by CliGen and does not have a default value" unless var.default_value %}
+              @{{var.id}} = {{var.default_value}}
+            {% end %}
+          {% end %}
+
+          {% if @type.has_method? :after_initialize %}
+            after_initialize
+          {% end %}
+        {% end %}
+      end
+    end
+  end
+end
diff --git a/src/cligen/command_node.cr b/src/cligen/command_node.cr
index c247cf0..4bcd8fd 100644
--- a/src/cligen/command_node.cr
+++ b/src/cligen/command_node.cr
@@ -29,7 +29,7 @@ module CliGen
       @pre_run_commands  : Array(RunCommand),
       @post_run_commands : Array(RunCommand),
       @description       : String? = nil
-    )
+      )
       @flags = (flags + CliGen::GLOBAL_FLAGS + @commands.flat_map(&.flags)).uniq
     end
 
@@ -67,8 +67,12 @@ module CliGen
       end
     end
 
-    def get(flag_long : String) : BaseFlag?
-      @flags.find{|f| f.long_key == flag_long}
+    def get(*, long : String) : BaseFlag?
+      @flags.find{|f| f.long_key == long}
+    end
+
+    def get(*, short : String) : BaseFlag?
+      @flags.find{|f| f.short == short}
     end
 
     def find_match(arg : String)
@@ -142,6 +146,11 @@ module CliGen
       {% end %}
     end
 
+    def verbose? : Bool
+      @verbose_flag ||= get(long: "--verbose").not_nil!.as(Flag(Bool))
+      @verbose_flag.not_nil!.value!
+    end
+
     def help : String
       {% begin %}
       {% if T.has_constant? "HELP_TEMPLATE" %}
@@ -162,8 +171,10 @@ module CliGen
       @flags.each(&.check!)
       check_for_duplicates!(@flags)
       @commands.each(&.check!)
+      {% unless T == Nil %}
       raise "ERROR : CommandNode({{T}})#check! : {{T}} has no subcommands and no #main defined" \
         if subcommands.empty? && !{{T.has_method?(:main)}}
+      {% end %}
     end
 
     def process(args : Array(CliGen::Arg)) : Nil
diff --git a/src/cligen/flag.cr b/src/cligen/flag.cr
index cd3a892..cb8ce08 100644
--- a/src/cligen/flag.cr
+++ b/src/cligen/flag.cr
@@ -1,6 +1,14 @@
 require "./arg"
 
 module CliGen
+  # To be able to store metadata for use in the help output
+  record FlagMeta,
+    type : String,
+    array : Bool,
+    format : String?,
+    default : String?,
+    options : Array(String)?
+
   abstract class BaseFlag
     getter var         : String
     getter short       : String?
@@ -9,6 +17,7 @@ module CliGen
     getter env_var     : String
     getter description : String
     getter delimiter   : String
+    getter meta        : FlagMeta
 
     def initialize(
       @var         : String,
@@ -16,7 +25,8 @@ module CliGen
       @long        : String,
       @env_var     : String,
       @description : String,
-      @delimiter   : String
+      @delimiter   : String,
+      @meta        : FlagMeta
       )
       # if the user provides just a "--long" I want the @long_key to match it
       if @long =~ /\s|=/
@@ -40,7 +50,7 @@ module CliGen
     @value    : T?
     @default  : T?
     @options  : Array(T)?
-    @validate : (T -> Bool)?
+    @validate : (T -> Bool)? 
     @on_match : Proc(Nil)?
     @format   : ::Regex?
 
@@ -57,7 +67,21 @@ module CliGen
       @on_match   : Proc(Nil)? = nil,
       @format     : ::Regex? = nil
       )
-      super(var, short, long, env_var, description, delimiter)
+      {% unless T.has_method? :to_s %}
+        {% raise "ERROR : Flag({{T}}, long: #{long}) : Error your flag type must have a to_s method" %}
+      {% end %}
+      {% if T <= Array %}
+        {% elem = T.type_vars.first %}
+        {% raise "ERROR : Flag({{T}}, long: #{long}) : Error your flag subtype must have a to_s method" unless elem.has_method? :to_s %}
+      {% end %}
+      meta = FlagMeta.new(
+        type: {{T.stringify}},
+        array: {{ T < Array ? true : false }},
+        options: {% if T < Array %} @options.try(&.first.map(&.to_s)) {% else %} @options.try(&.map(&.to_s)) {% end %},
+        default: @default.try(&.to_s),
+        format: @format.try(&.source)
+      )
+      super(var, short, long, env_var, description, delimiter, meta)
     end
 
     def requires_arg? : Bool
@@ -79,16 +103,31 @@ module CliGen
         argv.each do |arg|
           break if arg.flag?
           unless @format.nil?
-            unless arg.value =~ @format
-              puts "DEBUG : Flag({{T}}, long: #{@long_key}) : #{arg.value} was not found to be matching the defined filter #{@format}. So breaking from parse loop" if ENV["DEBUG"]
-              break
+            unless arg.value.includes?(@delimiter)
+              unless arg.value =~ @format
+                puts "DEBUG : Flag({{T}}, long: #{@long_key}) : #{arg.value} was not found to be matching the defined filter #{@format}. So breaking from parse loop" if ENV["DEBUG"]?
+                break
+              end
             end
           end
           {% if elem == Int32 %}
-            abort "ERROR : Flag({{T}}) : Provided arguemnt(#{arg.value}) was not an integer" unless arg.int?
-            (@value ||= [] of Int32) << arg.value.to_i
+            if arg.value.includes?(@delimiter) 
+              @value = (@value || [] of Int32) + arg.value.split(@delimiter).map(&.to_i32)
+            else
+              abort "ERROR : Flag({{T}}, long: #{@long_key}) : Provided arguemnt(#{arg.value}) was not an integer" unless arg.int?
+              (@value ||= [] of Int32) << arg.value.to_i
+            end
           {% elsif elem == String %}
-            (@value ||= [] of String) << arg.value
+            if arg.value.includes?(@delimiter) 
+              @value = (@value || [] of String) + arg.value.split(@delimiter).map{|v|
+                unless @format.nil?
+                  abort "ERROR : Flag({{T}}, long: #{@long_key} ) : Provided arguemnt(#{v}) did not match a valid fromat \"#{@format.not_nil!.source}\"" unless v =~ @format
+                end
+                v
+              }
+            else
+              (@value ||= [] of String) << arg.value
+            end
           {% elsif elem.class < CliGen::Coercable %}
           if arg.value.includes?(@delimiter) 
             @value = (@value || [] of {{elem}}) + arg.value.split(@delimiter).map{|i| {{elem}}.coerce(i)}
@@ -101,12 +140,17 @@ module CliGen
           arg.processed
         end
       {% elsif T == Int32 %}
+        abort "ERROR : Flag(#{T}, long: #{@long_key})  : #{argv.first.value} is not an int" unless argv.first.int?
         @value = argv.first.value.to_i
         argv.first.processed
       {% elsif T == Time %}
         @value = parse_time(argv.first.value)
         argv.first.processed
       {% elsif T == String %} # String
+        unless @format.nil?
+          abort "ERROR : Flag(#{T}, long: #{@long_key})  : #{argv.first.value} does not match a correct format #{@format.not_nil!.source}" unless argv.first.value =~ @format
+        end
+
         @value = argv.first.value
         argv.first.processed
       {% elsif T.class < CliGen::Parsable %}
@@ -161,11 +205,17 @@ module CliGen
       v = value!
 
       if opts = @options
-        abort "#{CliGen::APPNAME}: '#{v}' is not a valid value for #{@long_key} (valid: #{opts.join(", ")})" unless opts.includes?(v)
+        {% if T < Array %}
+          v.each do |v2|
+            abort "#{CliGen::APPNAME}: '#{v2}' is not a valid value for #{@long_key} (valid: #{opts.join(", ")})" unless opts.first.includes?(v2)
+          end
+        {% else %}
+          abort "#{CliGen::APPNAME}: '#{v}' is not a valid value for #{@long_key} (valid: #{opts.join(", ")})" unless opts.includes?(v)
+        {% end %}
       end
 
       if check = @validate
-        abort "#{CliGen::APPNAME}: validation failed for #{@long_key}" unless check.call(v)
+        abort "#{CliGen::APPNAME}: validation failed for #{@long_key} when testing #{v}" unless check.call(v)
       end
     end
 
diff --git a/src/cligen/global_flag.cr b/src/cligen/global_flag.cr
index 4b2ecc3..9242ff4 100644
--- a/src/cligen/global_flag.cr
+++ b/src/cligen/global_flag.cr
@@ -3,6 +3,15 @@ require "./flag"
 module CliGen
   GLOBAL_FLAGS = [] of BaseFlag
 
+  GLOBAL_FLAGS << Flag(Bool).new(
+    var: "",
+    short: "-v",
+    long: "--verbose",
+    env_var: "VERBOSE",
+    default: false,
+    description: "Enable verbose output from program & help output"
+  )
+
   macro add_global_flag(type, long, description, env_var = nil, short = nil, validation = nil, &on_match)
     {% raise "ERROR : CliGen.add_global_flag : type must be a TypeNode" unless type.is_a? TypeNode %}
     {% raise "ERROR : CliGen.add_global_flag : long must begin a StringLiteral" unless long.is_a? StringLiteral %}
diff --git a/src/cligen/template/cmd_help.ecr b/src/cligen/template/cmd_help.ecr
index 52ef103..9dda106 100644
--- a/src/cligen/template/cmd_help.ecr
+++ b/src/cligen/template/cmd_help.ecr
@@ -9,10 +9,21 @@ Description: <%= @description %>
 Flags:
 ---------------------------------------------------------------
 <%- @flags.each do |flag| -%>
-  <%- unless flag.short.nil? -%>
-    <%= "%-#{len}s %s" % ["#{flag.short.not_nil!.strip},#{flag.long.strip}", flag.description.strip] %>
+  <%- if flag.short.nil? -%>
+    <%- flags = [flag.long.strip] -%>
   <%- else -%>
-    <%= "%-#{len}s %s" % [flag.long.strip, flag.description.strip] %>
+    <%- flags = [flag.short,flag.long.strip] -%>
+  <%- end -%>
+    <%= "%-#{len}s %s" % [flags.join(","), flag.description.strip] %><%= flag.meta.options.nil? ? "" : " (valid: #{flag.meta.options.not_nil!.join(&.to_s)})" %><%= flag.meta.default.nil? ? "" : " (default: #{flag.meta.default})" %>
+  <%- if verbose? -%>
+    <%= "%-#{len}s %s" % ["", "Type: #{flag.meta.type}"] %>
+    <%= "%-#{len}s %s" % ["", "ENV VAR: #{flag.env_var}"] %>
+    <%- unless flag.meta.format.nil? -%>
+    <%= "%-#{len}s %s" % ["", "Valid Format: #{flag.meta.format}"] %>
+    <%- end -%>
+    <%- if flag.meta.array -%>
+    <%= "%-#{len}s %s" % ["", "Delimiter: #{flag.delimiter}"] %>
+    <%- end -%>
   <%- end -%>
 
 <%- end -%>