I've been a fan of the Kingdom Rush series for years, I've bought and beaten every game, and I think I have a good idea for the future of the series.
-Idea-
An ancient Greek mythology themed Kingdom Rush. I think this would go well with the series as it provides many enemies and heroes. Also, with Ironhide's past experience with Clash of the Olympians, I think it may be a viable option.
-Greek Gods-
For my idea, this game would provide the biggest option of final tower options in the series. Since it will use the 12 major Greek gods, (Zeus, Poseidon, Hades, Athena, Ares, Hera, Demeter, Apollo, Artemis, Aphrodite, Hephaestus, Hermes, and Dionysus), it could have either 12 final towers for each of the 4 tower groups (Bomb, Mage, Archer, and Barracks), or 3 final towers for each group. ( Personally I would prefer having 12 of each group )
-Towers-
Barracks
The barracks would start out as the militia barracks, producing weak farmers wielding rusted short swords, with nothing but clothing. That would upgrade to the Athenian barracks, hosting soldiers wearing iron armor, with small shields, helmets, and sharp short swords. That would then upgrade into the Spartan barracks,
hosting soldiers in bronze armor and helmets, with a red mowhawk and red cape, and bronze spears, which also gives the barracks a throwing ability.
Mages
The mage towers in this game don't change much, just the tower design and mage appearance.
Archers
The Archer towers would start out as the hunter tower, with poor equipment. Next is the Athenian archers, wielding iron bows and arrows. Then the Spartan archers, wielding heavy bronze long bows.
Bombers
In this the bomb towers would be potion throwers, starting out with just water filled glass bottles. That would then upgrade it to the Athenian Chemists, which would then start throwing an orange-y liquid that slows enemy units. Then, it would upgrade into the Spartan bombers, throwing blood-filled potions that slow units.
The End. I know it's kinda short, mostly because I really don't know what it takes to make a game, so just kinda fill in the blanks with the heroes, final towers, and enemies.