diff --git a/README.md b/README.md
index 263b941..f4f3a2a 100644
--- a/README.md
+++ b/README.md
@@ -1,31 +1,12 @@
 # bad-boy
-[![Clojars Project](https://img.shields.io/clojars/v/com.brunobonacci/bad-boy.svg)](https://clojars.org/com.brunobonacci/bad-boy) ![CircleCi](https://img.shields.io/circleci/project/BrunoBonacci/bad-boy.svg) ![last-commit](https://img.shields.io/github/last-commit/BrunoBonacci/bad-boy.svg) [![Dependencies Status](https://jarkeeper.com/com.brunobonacci/bad-boy/status.svg)](https://jarkeeper.com/BrunoBonacci/bad-boy)
 
-A cool library designed to ... well, that part is up to you.
+Chaos testing and infrastructure hardening tool.
 
 ## Usage
 
-In order to use the library add the dependency to your `project.clj`
+![bad boy](./doc/badboy.png)
 
-``` clojure
-;; Leiningen project
-[com.brunobonacci/bad-boy "0.1.0-SNAPSHOT"]
-
-;; deps.edn format
-{:deps { com.brunobonacci/bad-boy "0.1.0-SNAPSHOT" }}
-```
-
-Current version: [![Clojars Project](https://img.shields.io/clojars/v/com.brunobonacci/bad-boy.svg)](https://clojars.org/com.brunobonacci/bad-boy)
-
-
-Then require the namespace:
-
-``` clojure
-(ns foo.bar
-  (:require [com.brunobonacci.bad-boy :as x]))
-```
-
-Then it's up to you...
+Bad stuff in progress, more to come...!
 
 ## License
 
diff --git a/doc/badboy.png b/doc/badboy.png
new file mode 100644
index 0000000..7eea51a
Binary files /dev/null and b/doc/badboy.png differ
diff --git a/project.clj b/project.clj
index 183f45b..7b49492 100644
--- a/project.clj
+++ b/project.clj
@@ -8,12 +8,13 @@
 
   :scm {:name "git" :url "https://github.com/BrunoBonacci/bad-boy.git"}
 
-  :dependencies [[org.clojure/clojure "1.10.0"]
+  :dependencies [[org.clojure/clojure "1.10.1"]
                  [com.cognitect.aws/api       "0.8.301"]
                  [com.cognitect.aws/endpoints "1.1.11.537"]
                  [com.cognitect.aws/ec2       "714.2.430.0"]
                  [com.cognitect.aws/autoscaling "712.2.426.0"]
-                 [com.brunobonacci/where "0.5.1"]]
+                 [com.brunobonacci/where "0.5.1"]
+                 [instaparse "1.4.10"]]
 
   :global-vars {*warn-on-reflection* true}
 
diff --git a/resources/bad-boy.version b/resources/bad-boy.version
index d917d3e..b1e80bb 100644
--- a/resources/bad-boy.version
+++ b/resources/bad-boy.version
@@ -1 +1 @@
-0.1.2
+0.1.3
diff --git a/resources/cli-grammar.ebnf b/resources/cli-grammar.ebnf
new file mode 100644
index 0000000..139e44c
--- /dev/null
+++ b/resources/cli-grammar.ebnf
@@ -0,0 +1,18 @@
+command          = atom? (<ws> atom)*
+<atom>           = global-options | target
+
+<global-options> = global-option ( <ws> global-option )*
+<global-option>  = help | version | dryrun
+help             = <'-h'> | <'--help'>
+version          = <'-v'> | <'--version'>
+dryrun           = <'--dryrun'> | <'--dry-run'>
+
+target           = (target-name / tag)
+target-name      = glob
+                 
+tag              = <'tag:'> tag-name <'='> tag-value
+tag-name         = #'[a-zA-Z0-9_-]+'
+tag-value        = (<"'"> #"[^\']*" <"'">) | (<'"'> #'[^\"]*' <'"'>) | #'[a-zA-Z0-9_-]+'
+
+<glob>           = #'[a-zA-Z][a-zA-Z0-9*?_-]+'
+<ws>             = #'\s+'
diff --git a/src/com/brunobonacci/bad_boy.clj b/src/com/brunobonacci/bad_boy.clj
index 879bb50..555f8b3 100644
--- a/src/com/brunobonacci/bad_boy.clj
+++ b/src/com/brunobonacci/bad_boy.clj
@@ -7,7 +7,7 @@
   (:gen-class))
 
 ;;(def creds (credentials/system-property-credentials-provider))
-
+;;(reset! dry-run 1)
 
 
 (def ec2 (aws/client {:api :ec2}))
@@ -74,9 +74,9 @@
     #(aws-request asg
                   (cond-> {:op :DescribeAutoScalingGroups :request {:MaxRecords 100}}
                     % (assoc-in [:request :NextToken] %))))
-   (filter filters)
    (map #(select-keys % [:AutoScalingGroupName :MinSize :MaxSize :DesiredCapacity :Instances :Tags]))
-   (map #(update % :Tags tags-map))))
+   (map #(update % :Tags tags-map))
+   (filter filters)))
 
 
 
@@ -89,6 +89,7 @@
   (when (> (count c) 0)
     (clojure.core/rand-nth c)))
 
+
 (defn find-and-kill-one
   [asg ec2 filters]
   (let [groups (auto-scaling-groups asg filters)
@@ -131,8 +132,10 @@
   [& asg-names]
   (header asg-names)
   (if-not (seq asg-names)
-    (println "[no-op] No target selected, please provide a list of regex for autoscaling groups to target.!")
-    (let [filters (where
-                   (cons :or
-                         (map (fn [g] [:AutoScalingGroupName :MATCHES? g]) asg-names)))]
+    (println "[no-op] No target selected, please provide a list of regex for autoscaling groups to target, or use --default-selection !")
+    (let [filters (if (= "--default-selection" (first asg-names))
+                    (where (comp :chaos-testing :Tags) :is? "opt-in")
+                    (where
+                     (cons :or
+                           (map (fn [g] [:AutoScalingGroupName :MATCHES? g]) asg-names))))]
       (find-and-kill-one asg ec2 filters))))
diff --git a/src/com/brunobonacci/command_line.clj b/src/com/brunobonacci/command_line.clj
new file mode 100644
index 0000000..c0a34af
--- /dev/null
+++ b/src/com/brunobonacci/command_line.clj
@@ -0,0 +1,29 @@
+(ns com.brunobonacci.command-line
+  (:require [instaparse.core :as insta :refer [defparser]]
+            [clojure.java.io :as io]))
+
+
+(defparser parser (io/resource "cli-grammar.ebnf"))
+
+
+
+(defn parse-options
+  [cli]
+  (->> cli
+     (parser)
+     (insta/transform
+      {:help    #(vector :help    true)
+       :version #(vector :version true)
+       :dryrun  #(vector :dryrun  true)
+
+       :target-name  #(array-map :target-name %)
+       :tag (fn [[_ k] [_ v]] {:tag {k v}})
+
+       :command (fn [& args] (into {} args))
+       })))
+
+
+;;(parse-options "-h --version tag:chaos-testing='foo with space'")
+;;(parse-options "-h --version unlucky*-test")
+;;(parse-options "unlucky* --dryrun")
+;;