While the new towers do perform slightly differently--for example, the crossbowmen tower have a falcon upgrade that will enhance accuracy for neighboring towers--the fundamental gameplay elements remain unchanged.
Even the new enemies you'll confront--tribesman, mummies, and lizard people--require similar tactics to stop. If anything, I found more situations where my build placement was more forgiving in Frontiers than in Kingdom Rush as the enemies tend to appear in identical groups in the various pathways, with similar weaknesses. As an example, the original Kingdom Rush had missions where spiders would come down one path and trolls came down another--one type of tower exploited one enemy's weakness while tower took care of the other group. In Frontiers, I never had to be so careful with my placement.
The original Kingdom Rush introduced heroes after launch, but this time around the hero aspect is part of the game from the start. Not only can you earn stars to upgrade your arsenal, but also gems to buy emergency supplies like dynamite and coins to upgrade your heroes. (You can unlock three heroes as you progress, but the others must be purchased with real money.) The heroes are pretty much the only unit you can manipulate to move throughout the map, and the RPG aspects that Frontiers introduces to the heroes mechanic is one of the nicer surprises from the game.
It's hard to consider Kingdom Rush Frontiers a true sequel, but the amount of new levels, heroes, and content make it a worthy purchase in its own right. Over the several hours of the main campaign, you'll journey from the sandworm harrowed deserts of one land to a tribesman-infested jungle of another before finally going deep underground to rescue a dwarven mining party and ultimately stop a century's old demon. While perhaps a bit scattered at times and some of the charm wearing off the second time around, Kingdom Rush Frontiers is still one of the best tower defense and strategy games on the mobile platform.
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