diff --git a/src/corpus/mod.rs b/src/corpus/mod.rs
index 5fdf232020..81fc1d3cae 100644
--- a/src/corpus/mod.rs
+++ b/src/corpus/mod.rs
@@ -56,14 +56,14 @@ where
     }
 
     /// Gets a random entry
-    fn random_entry(&mut self) -> Result<&Rc<RefCell<Testcase<I>>>, AflError> {
+    fn random_entry(&mut self) -> Result<Rc<RefCell<Testcase<I>>>, AflError> {
         let len = { self.entries().len() };
         let id = self.rand_mut().below(len as u64) as usize;
-        Ok(self.entries_mut().get_mut(id).unwrap())
+        Ok(self.entries()[id].clone())
     }
 
     /// Gets the next entry (random by default)
-    fn get(&mut self) -> Result<&Rc<RefCell<Testcase<I>>>, AflError> {
+    fn get(&mut self) -> Result<Rc<RefCell<Testcase<I>>>, AflError> {
         self.random_entry()
     }
 }
@@ -257,12 +257,12 @@ where
     }
 
     /// Gets a random entry
-    fn random_entry(&mut self) -> Result<&Rc<RefCell<Testcase<I>>>, AflError> {
+    fn random_entry(&mut self) -> Result<Rc<RefCell<Testcase<I>>>, AflError> {
         self.corpus.random_entry()
     }
 
     /// Gets the next entry
-    fn get(&mut self) -> Result<&Rc<RefCell<Testcase<I>>>, AflError> {
+    fn get(&mut self) -> Result<Rc<RefCell<Testcase<I>>>, AflError> {
         if self.corpus.count() == 0 {
             return Err(AflError::Empty("Testcases".to_string()));
         }
@@ -271,7 +271,7 @@ where
             self.cycles = self.cycles + 1;
             self.pos = 0;
         }
-        Ok(self.corpus.entries_mut().get_mut(self.pos).unwrap())
+        Ok(self.corpus.entries()[self.pos].clone())
     }
 }
 
diff --git a/src/corpus/testcase.rs b/src/corpus/testcase.rs
index 83a23578f7..007b0dbbae 100644
--- a/src/corpus/testcase.rs
+++ b/src/corpus/testcase.rs
@@ -82,6 +82,11 @@ where
         &mut self.metadatas
     }
 
+    /// Add a metadata
+    pub fn add_metadata(&mut self, name: String, meta: Box<dyn TestcaseMetadata>) {
+        self.metadatas.insert(name, meta);
+    }
+
     /// Create a new DefaultTestcase instace given an input
     pub fn new(input: I) -> Self {
         Testcase {
diff --git a/src/engines/aflengine.rs b/src/engines/aflengine.rs
index f75057281e..5d97150e36 100644
--- a/src/engines/aflengine.rs
+++ b/src/engines/aflengine.rs
@@ -1,6 +1,6 @@
 use std::time;
 
-use crate::engines::Engine;
+use crate::engines::Evaluator;
 use crate::executors::Executor;
 use crate::feedbacks::Feedback;
 use crate::inputs::Input;
diff --git a/src/engines/mod.rs b/src/engines/mod.rs
index 415dab106a..3aa345f96b 100644
--- a/src/engines/mod.rs
+++ b/src/engines/mod.rs
@@ -1,16 +1,160 @@
-pub mod aflengine;
-
 use crate::corpus::testcase::Testcase;
+use crate::corpus::Corpus;
+use crate::executors::Executor;
+use crate::feedbacks::Feedback;
 use crate::inputs::Input;
+use crate::stages::Stage;
 use crate::AflError;
 
 use std::cell::RefCell;
 use std::rc::Rc;
 
-pub trait Engine<'a, I>
+pub trait Evaluator<I>
 where
     I: Input,
 {
-    fn execute(&mut self, input: &mut I, entry: Rc<RefCell<Testcase<I>>>)
-        -> Result<bool, AflError>;
+    fn evaluate_input(
+        &mut self,
+        input: &mut I,
+        entry: Rc<RefCell<Testcase<I>>>,
+    ) -> Result<bool, AflError>;
+}
+
+pub trait Engine<'a, I, C, E>: Evaluator<I>
+where
+    I: Input,
+    C: Corpus<I>,
+    E: Executor<I>,
+{
+    fn feedbacks(&self) -> &Vec<Box<dyn Feedback<I>>>;
+
+    fn feedbacks_mut(&mut self) -> &mut Vec<Box<dyn Feedback<I>>>;
+
+    fn add_feedback(&mut self, feedback: Box<dyn Feedback<I>>) {
+        self.feedbacks_mut().push(feedback);
+    }
+
+    fn stages(&self) -> &Vec<Box<dyn Stage<'a, I, E = Self>>>;
+
+    fn stages_mut(&mut self) -> &mut Vec<Box<dyn Stage<'a, I, E = Self>>>;
+
+    fn add_stage(&mut self, stage: Box<dyn Stage<'a, I, E = Self>>) {
+        self.stages_mut().push(stage);
+    }
+
+    fn corpus(&self) -> &C;
+
+    fn corpus_mut(&mut self) -> &mut C;
+
+    fn executor(&self) -> &E;
+
+    fn executor_mut(&mut self) -> &mut E;
+
+    fn fuzz_one(&mut self) -> Result<(), AflError> {
+        let entry = self.corpus_mut().get()?;
+        for stage in self.stages_mut() {
+            stage.perform(entry.clone())?;
+        }
+        Ok(())
+    }
+
+    fn evaluate_input_engine(
+        &mut self,
+        input: &mut I,
+        entry: Rc<RefCell<Testcase<I>>>,
+    ) -> Result<bool, AflError> {
+        {
+            self.executor_mut().reset_observers()?;
+            // self.executor_mut().place_input(Box::new(input))?;
+
+            self.executor_mut().run_target()?;
+
+            self.executor_mut().post_exec_observers()?;
+        }
+
+        // TODO new method for this shit
+        let mut new_entry: Option<Rc<RefCell<Testcase<I>>>> = None; // lazy init
+        let mut rate_acc = 0;
+        for feedback in self.feedbacks_mut() {
+            let (rate, meta) = feedback.is_interesting(self.executor_mut());
+            rate_acc += rate;
+            if let Some(m) = meta {
+                //if new_entry.is_none() {
+                new_entry = Some(Rc::new(RefCell::new(Testcase::<I>::new(input.clone()))));
+                //}
+                new_entry
+                    .unwrap()
+                    .borrow_mut()
+                    .add_metadata("test".to_string(), m);
+            }
+        }
+
+        Ok(true)
+    }
+}
+
+pub struct DefaultEngine<'a, I, C, E>
+where
+    I: Input,
+    C: Corpus<I>,
+    E: Executor<I>,
+{
+    feedbacks: Vec<Box<dyn Feedback<I>>>,
+    stages: Vec<Box<dyn Stage<'a, I, E = Self>>>,
+    executor: &'a mut E,
+    corpus: &'a mut C,
+}
+
+impl<'a, I, C, E> Evaluator<I> for DefaultEngine<'a, I, C, E>
+where
+    I: Input,
+    C: Corpus<I>,
+    E: Executor<I>,
+{
+    fn evaluate_input(
+        &mut self,
+        input: &mut I,
+        entry: Rc<RefCell<Testcase<I>>>,
+    ) -> Result<bool, AflError> {
+        self.evaluate_input_engine(input, entry)
+    }
+}
+
+impl<'a, I, C, E> Engine<'a, I, C, E> for DefaultEngine<'a, I, C, E>
+where
+    I: Input,
+    C: Corpus<I>,
+    E: Executor<I>,
+{
+    fn feedbacks(&self) -> &Vec<Box<dyn Feedback<I>>> {
+        &self.feedbacks
+    }
+
+    fn feedbacks_mut(&mut self) -> &mut Vec<Box<dyn Feedback<I>>> {
+        &mut self.feedbacks
+    }
+
+    fn stages(&self) -> &Vec<Box<dyn Stage<'a, I, E = Self>>> {
+        &self.stages
+    }
+
+    fn stages_mut(&mut self) -> &mut Vec<Box<dyn Stage<'a, I, E = Self>>> {
+        &mut self.stages
+    }
+
+    fn corpus(&self) -> &C {
+        self.corpus
+    }
+
+    fn corpus_mut(&mut self) -> &mut C {
+        self.corpus
+    }
+
+    fn executor(&self) -> &E {
+        self.executor
+    }
+
+    fn executor_mut(&mut self) -> &mut E {
+        self.executor
+    }
 }
diff --git a/src/executors/inmemory.rs b/src/executors/inmemory.rs
index dc6afca1c6..a4c9d3adad 100644
--- a/src/executors/inmemory.rs
+++ b/src/executors/inmemory.rs
@@ -193,7 +193,6 @@ mod tests {
     use crate::inputs::Input;
     use crate::observers::Observer;
     use crate::AflError;
-    use std::any::Any;
 
     #[derive(Clone)]
     struct NopInput {}
diff --git a/src/feedbacks/mod.rs b/src/feedbacks/mod.rs
index 683565b717..dfc92aa7e7 100644
--- a/src/feedbacks/mod.rs
+++ b/src/feedbacks/mod.rs
@@ -1,6 +1,6 @@
 extern crate num;
 
-use crate::corpus::Testcase;
+use crate::corpus::{Testcase, TestcaseMetadata};
 use crate::executors::Executor;
 use crate::inputs::Input;
 use crate::observers::MapObserver;
@@ -14,9 +14,13 @@ where
     I: Input,
 {
     /// is_interesting should return the "Interestingness" from 0 to 255 (percent times 2.55)
-    fn is_interesting(&mut self, executor: &dyn Executor<I>, entry: &Testcase<I>) -> u8;
+    fn is_interesting(
+        &mut self,
+        executor: &dyn Executor<I>,
+    ) -> (u32, Option<Box<dyn TestcaseMetadata>>);
 }
 
+/// A Reducer function is used to aggregate values for the novelty search
 pub trait Reducer<T>
 where
     T: Integer + Copy + 'static,
@@ -86,7 +90,10 @@ where
     O: MapObserver<T>,
     I: Input,
 {
-    fn is_interesting(&mut self, _executor: &dyn Executor<I>, _entry: &Testcase<I>) -> u8 {
+    fn is_interesting(
+        &mut self,
+        _executor: &dyn Executor<I>,
+    ) -> (u32, Option<Box<dyn TestcaseMetadata>>) {
         let mut interesting = 0;
 
         // TODO: impl. correctly, optimize
@@ -101,11 +108,11 @@ where
                 *history = reduced;
                 interesting += 25;
                 if interesting >= 250 {
-                    return 255;
+                    return (255, None);
                 }
             }
         }
-        interesting
+        (interesting, None)
     }
 }
 
diff --git a/src/stages/mod.rs b/src/stages/mod.rs
index b589e05871..4b6a71f0ca 100644
--- a/src/stages/mod.rs
+++ b/src/stages/mod.rs
@@ -1,25 +1,25 @@
 pub mod mutational;
 
 use crate::corpus::Testcase;
-use crate::engines::Engine;
+use crate::engines::Evaluator;
 use crate::inputs::Input;
 use crate::AflError;
 
 use std::cell::RefCell;
 use std::rc::Rc;
 
-pub trait HasEngine<'a, I>
+pub trait HasEvaluator<I>
 where
     I: Input,
 {
-    type E: Engine<'a, I>;
+    type E: Evaluator<I>;
 
-    fn engine(&self) -> &Self::E;
+    fn eval(&self) -> &Self::E;
 
-    fn engine_mut(&mut self) -> &mut Self::E;
+    fn eval_mut(&mut self) -> &mut Self::E;
 }
 
-pub trait Stage<'a, I>: HasEngine<'a, I>
+pub trait Stage<'a, I>: HasEvaluator<I>
 where
     I: Input,
 {
diff --git a/src/stages/mutational.rs b/src/stages/mutational.rs
index ec36c60133..cdad856d23 100644
--- a/src/stages/mutational.rs
+++ b/src/stages/mutational.rs
@@ -1,8 +1,8 @@
 use crate::corpus::testcase::Testcase;
-use crate::engines::Engine;
+use crate::engines::Evaluator;
 use crate::inputs::Input;
 use crate::mutators::Mutator;
-use crate::stages::{HasEngine, Stage};
+use crate::stages::{HasEvaluator, Stage};
 use crate::utils::{HasRand, Rand};
 use crate::AflError;
 
@@ -36,7 +36,7 @@ where
                 m.mutate(&mut input, i as i32)?;
             }
 
-            let interesting = self.engine_mut().execute(&mut input, entry.clone())?;
+            let interesting = self.eval_mut().evaluate_input(&mut input, entry.clone())?;
 
             for m in self.mutators_mut() {
                 m.post_exec(interesting, i as i32)?;
@@ -52,10 +52,10 @@ pub struct DefaultMutationalStage<'a, I, R, E>
 where
     I: Input,
     R: Rand,
-    E: Engine<'a, I>,
+    E: Evaluator<I>,
 {
     rand: &'a mut R,
-    engine: &'a mut E,
+    eval: &'a mut E,
     mutators: Vec<Box<dyn Mutator<I, R = R>>>,
 }
 
@@ -63,7 +63,7 @@ impl<'a, I, R, E> HasRand for DefaultMutationalStage<'a, I, R, E>
 where
     I: Input,
     R: Rand,
-    E: Engine<'a, I>,
+    E: Evaluator<I>,
 {
     type R = R;
 
@@ -75,20 +75,20 @@ where
     }
 }
 
-impl<'a, I, R, E> HasEngine<'a, I> for DefaultMutationalStage<'a, I, R, E>
+impl<'a, I, R, E> HasEvaluator<I> for DefaultMutationalStage<'a, I, R, E>
 where
     I: Input,
     R: Rand,
-    E: Engine<'a, I>,
+    E: Evaluator<I>,
 {
     type E = E;
 
-    fn engine(&self) -> &Self::E {
-        self.engine
+    fn eval(&self) -> &Self::E {
+        self.eval
     }
 
-    fn engine_mut(&mut self) -> &mut Self::E {
-        self.engine
+    fn eval_mut(&mut self) -> &mut Self::E {
+        self.eval
     }
 }
 
@@ -96,7 +96,7 @@ impl<'a, I, R, E> MutationalStage<'a, I> for DefaultMutationalStage<'a, I, R, E>
 where
     I: Input,
     R: Rand,
-    E: Engine<'a, I>,
+    E: Evaluator<I>,
 {
     fn mutators(&self) -> &Vec<Box<dyn Mutator<I, R = Self::R>>> {
         &self.mutators
@@ -111,7 +111,7 @@ impl<'a, I, R, E> Stage<'a, I> for DefaultMutationalStage<'a, I, R, E>
 where
     I: Input,
     R: Rand,
-    E: Engine<'a, I>,
+    E: Evaluator<I>,
 {
     fn perform(&mut self, entry: Rc<RefCell<Testcase<I>>>) -> Result<(), AflError> {
         self.perform_mutational(entry)
@@ -122,12 +122,12 @@ impl<'a, I, R, E> DefaultMutationalStage<'a, I, R, E>
 where
     I: Input,
     R: Rand,
-    E: Engine<'a, I>,
+    E: Evaluator<I>,
 {
-    pub fn new(rand: &'a mut R, engine: &'a mut E) -> Self {
+    pub fn new(rand: &'a mut R, eval: &'a mut E) -> Self {
         DefaultMutationalStage {
             rand: rand,
-            engine: engine,
+            eval: eval,
             mutators: vec![],
         }
     }