Use simple Akka actors from the REPL. I should probably also illustrate a simple sbt project that just depends on Akka to make starting a repl with akka easy

SimpleActorsFromTheRepl

import akka.actor._
// need an actor system, make it implicit to it's used by all our repl based actors
implicit val system = ActorSystem("replActorSystem")

// this gives us an easy way to define simple actors
import ActorDSL._

// here's a simple example of creating an actor
// Also, this will give us a simple actor that is used to print the 
// results sent back to us from the other actors.
implicit val sender = actor(new Act { become { case msg => println(msg) } } )

// Another actor to talk to 
val anotherActor = actor(new Act { become { case msg => sender ! s"I heard you say: $msg" }})

// Now send the other actor something 
anotherActor ! "a simple string message"

// And you'll see the below, shown in a comment so you can copy & paste all of this into your repl window
// scala> I heard you say: a simple string message
// Note you see the response because of our implicit sender defined above. 

At line #3 REPL throws:
com.typesafe.config.ConfigException$Missing: No configuration setting found for key 'akka'