User blog comment:StarryStar34/BTD4 Idea 1: Add the ZOMG/@comment-1785597-20120528163111/@comment-4795804-20120530081148

Exactly, as Anomalous13 said. Earlier BTD games have less possibilities to upgrade towers, thus bloons are less "developed" there. Even ordinary Black Bloons & White Bloons can make serious problems to the player in BTD1.