There is one more engineer left, I clicked the calender next to the wave number " In addition to that, I’ve added a “Fail Safe” button. If the game bugs out, or you have one troop hitting you out of range, or enemies stuck, click the CALENDAR beside the WAVE COUNTER. That button will cause the enemies to all find a new path, and should fix those errors if they occur during your game!" and he wouldn't move. You need to make the engineers not try and demolish everything in their path because it glitched on me.
 "Master of Fortresses"){kind=icon}
 "Weapon"){kind=icon}
 "Bowmaster Prelude"){kind=icon}