diff --git a/cline.go b/cline.go
index 0a2da75..c160f36 100644
--- a/cline.go
+++ b/cline.go
@@ -62,43 +62,54 @@ func New() *App {
 	return &App{}
 }
 
+// validateCommands checks if a command is valid and initialize it
+func validateCommands(commands []Cmd) ([]Cmd, error) {
+	var cmds []Cmd
+	for _, c := range commands {
+		name := strings.TrimSpace(c.Name)
+		if name == "" {
+			return nil, fmt.Errorf("command name has empty value")
+		}
+		cflags, err := validateAndInitFlags(c.Flags)
+		if err != nil {
+			return nil, err
+		}
+		c.Flags = cflags
+		cmds = append(cmds, c)
+	}
+	return cmds, nil
+}
+
 // Run executes the current application.
 func (app *App) Run(vArgs []string) error {
 	// Commands and flags validation
 
-	// 1. Check application flags
-	aflags, err := checkAndInitFlags(app.Flags)
+	// 1. Check application global flags
+	vflags, err := validateAndInitFlags(app.Flags)
 	if err != nil {
 		return err
 	}
-	app.Flags = aflags
+	app.Flags = vflags
 
 	// 2. Check commands and their flags
-	var cmds []Cmd
-	for _, c := range app.Commands {
-		name := strings.ToLower(strings.TrimSpace(c.Name))
-		if name == "" {
-			return fmt.Errorf("command name has empty value")
-		}
-		cflags, err := checkAndInitFlags(c.Flags)
-		if err != nil {
-			return err
-		}
-		c.Flags = cflags
-		cmds = append(cmds, c)
+	vcmds, err := validateCommands(app.Commands)
+	if err != nil {
+		return err
 	}
-	app.Commands = cmds
+	app.Commands = vcmds
 
 	// 3. Process commands and flags
 	var lastCmd Cmd
 	var lastFlag Flag
+	var lastFlagIndex int = -1
+	// var lastCmdFlagList []Flag
 	var tailArgs []string
-	var hasCommand = false
+	var hasCmd = false
 	var hasHelp = false
 	var hasVersion = false
 
 	for i := 1; i < len(vArgs); i++ {
-		arg := strings.ToLower(strings.TrimSpace(vArgs[i]))
+		arg := strings.TrimSpace(vArgs[i])
 
 		// Check for no supported arguments (remaining)
 		if len(tailArgs) > 0 {
@@ -110,7 +121,7 @@ func (app *App) Run(vArgs []string) error {
 		if strings.HasPrefix(arg, "-") {
 			flagKey := strings.TrimPrefix(strings.TrimPrefix(arg, "-"), "-")
 			// Skip unsupported fags
-			if strings.HasPrefix(flagKey, "-") {
+			if flagKey == "" || strings.HasPrefix(flagKey, "-") {
 				tailArgs = append(tailArgs, arg)
 				continue
 			}
@@ -120,7 +131,9 @@ func (app *App) Run(vArgs []string) error {
 			case "help", "h":
 				hasHelp = true
 			case "version", "v":
-				hasVersion = true
+				if !hasCmd {
+					hasVersion = true
+				}
 			}
 			if hasHelp || hasVersion {
 				break
@@ -128,32 +141,63 @@ func (app *App) Run(vArgs []string) error {
 
 			// Assign flag default values
 			var flags []Flag
-			if hasCommand {
+			if hasCmd {
 				flags = lastCmd.Flags
 			} else {
 				flags = app.Flags
 			}
 
 			// Find argument key flag on flag list
-			flag := findFlagByKey(flagKey, flags)
+			i, flag := findFlagByKey(flagKey, flags)
 			if flag == nil {
 				return fmt.Errorf("argument `%s` is not recognised", arg)
 			}
 			lastFlag = flag
+			lastFlagIndex = i
+
+			switch fl := lastFlag.(type) {
+			case FlagBool:
+				if fl.Name != "" {
+					if fl.zflagAssigned {
+						tailArgs = append(tailArgs, arg)
+						continue
+					}
+
+					// If bool flag is defined is assumed as `true`
+					s := FlagValue("1")
+					fl.zflag = s
+					fl.zflagAssigned = true
+					lastFlag = fl
+
+					if hasCmd {
+						if len(lastCmd.Flags) > 0 && lastFlagIndex > -1 {
+							lastCmd.Flags[lastFlagIndex] = fl
+						}
+					} else {
+						if len(app.Flags) > 0 && lastFlagIndex > -1 {
+							app.Flags[lastFlagIndex] = fl
+						}
+					}
+
+					tailArgs = append(tailArgs, arg)
+					continue
+				}
+			}
+
 			continue
 		}
 
 		// 3.2. Commands
 		// 3.2.1 Check for a valid command (first time)
-		if !hasCommand {
+		if !hasCmd {
 			for _, c := range app.Commands {
 				if c.Name == arg {
-					hasCommand = true
+					hasCmd = true
 					lastCmd = c
 					break
 				}
 			}
-			if hasCommand {
+			if hasCmd {
 				continue
 			}
 		}
@@ -172,14 +216,24 @@ func (app *App) Run(vArgs []string) error {
 					tailArgs = append(tailArgs, arg)
 					continue
 				}
-				s := FlagValue(arg)
-				if _, err := s.Bool(); err == nil {
-					fl.zflag = s
-					fl.zflagAssigned = true
-					lastFlag = fl
+
+				// If bool flag is defined is assumed as `true`
+				s := FlagValue("1")
+				fl.zflag = s
+				fl.zflagAssigned = true
+				lastFlag = fl
+
+				if hasCmd {
+					if len(lastCmd.Flags) > 0 && lastFlagIndex > -1 {
+						lastCmd.Flags[lastFlagIndex] = fl
+					}
 				} else {
-					tailArgs = append(tailArgs, arg)
+					if len(app.Flags) > 0 && lastFlagIndex > -1 {
+						app.Flags[lastFlagIndex] = fl
+					}
 				}
+
+				tailArgs = append(tailArgs, arg)
 				continue
 			}
 		case FlagInt:
@@ -193,6 +247,16 @@ func (app *App) Run(vArgs []string) error {
 					fl.zflag = s
 					fl.zflagAssigned = true
 					lastFlag = fl
+
+					if hasCmd {
+						if len(lastCmd.Flags) > 0 && lastFlagIndex > -1 {
+							lastCmd.Flags[lastFlagIndex] = fl
+						}
+					} else {
+						if len(app.Flags) > 0 && lastFlagIndex > -1 {
+							app.Flags[lastFlagIndex] = fl
+						}
+					}
 				} else {
 					tailArgs = append(tailArgs, arg)
 				}
@@ -207,6 +271,16 @@ func (app *App) Run(vArgs []string) error {
 				fl.zflag = FlagValue(arg)
 				fl.zflagAssigned = true
 				lastFlag = fl
+
+				if hasCmd {
+					if len(lastCmd.Flags) > 0 && lastFlagIndex > -1 {
+						lastCmd.Flags[lastFlagIndex] = fl
+					}
+				} else {
+					if len(app.Flags) > 0 && lastFlagIndex > -1 {
+						app.Flags[lastFlagIndex] = fl
+					}
+				}
 				continue
 			}
 		case FlagStringSlice:
@@ -218,6 +292,16 @@ func (app *App) Run(vArgs []string) error {
 				fl.zflag = FlagValue(arg)
 				fl.zflagAssigned = true
 				lastFlag = fl
+
+				if hasCmd {
+					if len(lastCmd.Flags) > 0 && lastFlagIndex > -1 {
+						lastCmd.Flags[lastFlagIndex] = fl
+					}
+				} else {
+					if len(app.Flags) > 0 && lastFlagIndex > -1 {
+						app.Flags[lastFlagIndex] = fl
+					}
+				}
 				continue
 			}
 		default:
@@ -228,7 +312,11 @@ func (app *App) Run(vArgs []string) error {
 
 	// Show `help` flag details
 	if hasHelp {
-		return app.printHelp()
+		if hasCmd {
+			return printHelp(app, &lastCmd)
+		}
+
+		return printHelp(app, nil)
 	}
 
 	// Show `version` flag details
@@ -238,7 +326,7 @@ func (app *App) Run(vArgs []string) error {
 	}
 
 	// Call command handler
-	if hasCommand && lastCmd.Handler != nil {
+	if hasCmd && lastCmd.Handler != nil {
 		return lastCmd.Handler(&CmdContext{
 			Cmd: &lastCmd,
 			Flags: &FlagMapValues{
diff --git a/examples/main.go b/examples/main.go
index 62e60d7..d784f99 100644
--- a/examples/main.go
+++ b/examples/main.go
@@ -31,7 +31,7 @@ func main() {
 			Name:    "verbose",
 			Summary: "Enable more verbose info",
 			Value:   false,
-			Aliases: []string{"v"},
+			Aliases: []string{"V"},
 			EnvVar:  "ENV_VERBOSE",
 		},
 	}
@@ -41,10 +41,10 @@ func main() {
 			Summary: "Show command information",
 			Flags: []cli.Flag{
 				cli.FlagInt{
-					Name:    "version",
-					Summary: "Enable more verbose command information",
+					Name:    "trace",
+					Summary: "Enable tracing mode",
 					Value:   10,
-					Aliases: []string{"z"},
+					Aliases: []string{"t"},
 				},
 				cli.FlagBool{
 					Name:    "detailed",
@@ -61,6 +61,9 @@ func main() {
 					os.Exit(1)
 				}
 				fmt.Printf("Cmd Flag `version` opted: `%d` (%T)\n", i, i)
+
+				d := ctx.Flags.String("detailed")
+				fmt.Printf("Cmd Flag `detailed` opted: `%s` (%T)\n", d, d)
 				fmt.Printf("Cmd Tail arguments: %#v\n", ctx.TailArgs)
 				return nil
 			},
@@ -70,7 +73,10 @@ func main() {
 		fmt.Printf("App `%s` executed!\n", ctx.App.Name)
 		fmt.Printf("App Tail arguments: %#v\n", ctx.TailArgs)
 		fmt.Printf("App Flag `file` opted: `%s`\n", ctx.Flags.StringSlice("file"))
-		fmt.Printf("App Flag `verbose` opted: `%s`\n", ctx.Flags.StringSlice("verbose"))
+
+		b, _ := ctx.Flags.Bool("verbose")
+
+		fmt.Printf("App Flag `verbose` opted: `%v`\n", b)
 		return nil
 	}
 	if err := app.Run(os.Args); err != nil {
diff --git a/flag_helpers.go b/flag_helpers.go
index fa04e5e..d56ec38 100644
--- a/flag_helpers.go
+++ b/flag_helpers.go
@@ -5,8 +5,8 @@ import (
 	"strings"
 )
 
-// checkAndInitFlags checks for a flag and initialize it
-func checkAndInitFlags(flags []Flag) ([]Flag, error) {
+// validateAndInitFlags checks for a flag and initialize it
+func validateAndInitFlags(flags []Flag) ([]Flag, error) {
 	var sFlags []Flag
 	for _, v := range flags {
 		switch f := v.(type) {
@@ -46,54 +46,54 @@ func checkAndInitFlags(flags []Flag) ([]Flag, error) {
 }
 
 // findFlagByKey finds a flag item in a flag's array by key.
-func findFlagByKey(key string, flags []Flag) Flag {
-	for _, f := range flags {
+func findFlagByKey(key string, flags []Flag) (int, Flag) {
+	for i, f := range flags {
 		switch fl := f.(type) {
 		case FlagBool:
 			// Check for long named flags
 			if key == fl.Name {
-				return fl
+				return i, fl
 			}
 			// Check for short named flags
 			for _, s := range fl.Aliases {
 				if key == s {
-					return fl
+					return i, fl
 				}
 			}
 		case FlagInt:
 			// Check for long named flags
 			if key == fl.Name {
-				return fl
+				return i, fl
 			}
 			// Check for short named flags
 			for _, s := range fl.Aliases {
 				if key == s {
-					return fl
+					return i, fl
 				}
 			}
 		case FlagString:
 			// Check for long named flags
 			if key == fl.Name {
-				return fl
+				return i, fl
 			}
 			// Check for short named flags
 			for _, s := range fl.Aliases {
 				if key == s {
-					return fl
+					return i, fl
 				}
 			}
 		case FlagStringSlice:
 			// Check for long named flags
 			if key == fl.Name {
-				return fl
+				return i, fl
 			}
 			// Check for short named flags
 			for _, s := range fl.Aliases {
 				if key == s {
-					return fl
+					return i, fl
 				}
 			}
 		}
 	}
-	return nil
+	return -1, nil
 }
diff --git a/print_help.go b/print_help.go
index 367684b..18f2494 100644
--- a/print_help.go
+++ b/print_help.go
@@ -5,31 +5,47 @@ import (
 	"strings"
 )
 
-// printHelp prints current application flags and commands (--help).
-func (app *App) printHelp() error {
-	fmt.Printf("NAME: %s [OPTIONS] COMMAND\n\n", app.Name)
-	fmt.Printf("%s\n\n", app.Summary)
+// printHelp prints current application flags and commands info (--help).
+func printHelp(app *App, cmd *Cmd) error {
+	var summary string
+	var flags []Flag
+
+	if cmd == nil {
+		summary = app.Summary
+		flags = app.Flags
+	} else {
+		summary = cmd.Summary
+		flags = cmd.Flags
+	}
+
+	// TODO: subcommands support
+	if cmd == nil {
+		fmt.Printf("NAME: %s [OPTIONS] COMMAND\n\n", app.Name)
+	} else {
+		fmt.Printf("NAME: %s %s [OPTIONS] COMMAND\n\n", app.Name, cmd.Name)
+	}
+	fmt.Printf("%s\n\n", summary)
 
 	// Print options
 	fmt.Printf("OPTIONS:\n")
 
-	var flags [][]string
+	var vflags [][]string
 	var flagLen int = 0
-	for _, fl := range app.Flags {
+	for _, fl := range flags {
 		fname := ""
 		switch f := fl.(type) {
 		case FlagBool:
 			fname = f.Name
-			flags = append(flags, []string{f.Name, f.Summary})
+			vflags = append(vflags, []string{f.Name, f.Summary})
 		case FlagInt:
 			fname = f.Name
-			flags = append(flags, []string{f.Name, f.Summary})
+			vflags = append(vflags, []string{f.Name, f.Summary})
 		case FlagString:
 			fname = f.Name
-			flags = append(flags, []string{f.Name, f.Summary})
+			vflags = append(vflags, []string{f.Name, f.Summary})
 		case FlagStringSlice:
 			fname = f.Name
-			flags = append(flags, []string{f.Name, f.Summary})
+			vflags = append(vflags, []string{f.Name, f.Summary})
 		}
 		if len([]rune(fname)) > flagLen {
 			flagLen = len([]rune(fname))
@@ -41,31 +57,55 @@ func (app *App) printHelp() error {
 	if len([]rune("help")) > flagLen {
 		flagLen = len([]rune("help"))
 	}
-	for _, f := range flags {
-		fmt.Printf("  --%s%s    %s\n", f[0], strings.Repeat(" ", flagLen-len([]rune(f[0]))), f[1])
+	for _, f := range vflags {
+		fmt.Printf(
+			"  --%s%s    %s\n",
+			f[0],
+			strings.Repeat(" ", flagLen-len([]rune(f[0]))),
+			f[1],
+		)
 	}
 
-	// Print special flags
-	fmt.Printf("  --%s%s    %s\n", "version", strings.Repeat(" ", flagLen-len([]rune("version"))), "Prints version information")
-	fmt.Printf("  --%s%s    %s\n", "help", strings.Repeat(" ", flagLen-len([]rune("help"))), "Prints help information")
+	// App with commands
+	if cmd == nil {
+		// Print special flags
+		fmt.Printf(
+			"  --%s%s    %s\n",
+			"version",
+			strings.Repeat(" ", flagLen-len([]rune("version"))),
+			"Prints version information",
+		)
+		fmt.Printf(
+			"  --%s%s    %s\n",
+			"help",
+			strings.Repeat(" ", flagLen-len([]rune("help"))),
+			"Prints help information",
+		)
 
-	// Print commands
-	fmt.Printf("\n")
-	fmt.Printf("COMMANDS:\n")
+		// Print commands
+		fmt.Printf("\n")
+		fmt.Printf("COMMANDS:\n")
 
-	var cmds [][]string
-	var cmdLen int = 0
-	for _, c := range app.Commands {
-		cmds = append(cmds, []string{c.Name, c.Summary})
-		if len([]rune(c.Name)) > cmdLen {
-			cmdLen = len([]rune(c.Name))
+		var vcmds [][]string
+		var cmdLen int = 0
+		for _, c := range app.Commands {
+			vcmds = append(vcmds, []string{c.Name, c.Summary})
+			if len([]rune(c.Name)) > cmdLen {
+				cmdLen = len([]rune(c.Name))
+			}
 		}
-	}
-	for _, c := range cmds {
-		fmt.Printf("  %s%s    %s\n", c[0], strings.Repeat(" ", cmdLen-len([]rune(c[0]))), c[1])
+		for _, c := range vcmds {
+			fmt.Printf("  %s%s    %s\n", c[0], strings.Repeat(
+				" ", cmdLen-len([]rune(c[0]))), c[1],
+			)
+		}
+
+		fmt.Printf("\n")
+		fmt.Printf("Run '%s COMMAND --help' for more information on a command\n", app.Name)
+	} else {
+		fmt.Printf("\n")
+		fmt.Printf("Run '%s %s COMMAND --help' for more information on a command\n", app.Name, cmd.Name)
 	}
 
-	fmt.Printf("\n")
-	fmt.Printf("Run '%s COMMAND --help' for more information on a command\n", app.Name)
 	return nil
 }