The game isn't deep as far as I can tell. My youngest kid (5) loves it when I play it though, the somewhat older kds enjoy it too. The strategy does vary from level to level along with the difficulty. The element that really pushes it to four stars though is that the narrator has a such a perfect voice and delivers lines that are funny. There are many references to major fantasy writings and parodying them. Gameplay itself is a typical RTS game with mission elements. Go out there and beat the good guys! It's the Ultimate Evil game. For those who care, there is some PG level language and innuendo. The violence is cartoonish.
Kingdom Rush has an enjoyable formula they follow, and this is just a enough different in terms of enemies and abilities to be a good addition to the series. If you enjoyed the other Kingdom Rush games you will enjoy this one. I like that seeing the younger versions of well liked characteers too.