This challenge is simple: In WC3/4, playing at any level higher than Veteran, complete the ENTIRE game using only ONE type of ship. The "one type" rule applies for any mission in which you are allowed a choice of ship--for atmospheric or scramble missions, and a couple of others, you are not allowed to choose your ship. Choose whichever you like--Arrow, Hellcat, Thunderbolt, or Longbow for WC3, or Banshee, Vindicator, or Avenger for WC4. So far I have managed this on Ace level for Arrow and Thunderbolt in WC3, and for Banshee, Vindicator, and Avenger in WC4.