title: Optional activity and repeating activity for different actors in an activity diagram
body: <p>I've got a game that I'm trying to create an activity diagram for but I run into some problems.</p>
  <p>My try so far looks like this:
  <a href="https://i.stack.imgur.com/SL7zr.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/SL7zr.png" alt="My try so far" /></a></p>
  
  <p>This shows the flow good, the GUI is created -&gt; Player performs actions one -&gt; Action Two -&gt; Ends turn.</p>
  <p>But what I don't really like is how I could solve action 3. It is suppose to be optional and can be performed anytime from the &quot;System creates GUI&quot; action up until &quot;Player ends turn&quot;. Though, performing action three still doesn't move the player back or forth in the &quot;main cycle&quot;.</p>
  <p>The game has 4 players that go through the same cycle but I'm not sure this is a very good way to do it.</p>