I had a dream that a new area was found in RR2: The Deep Science Division. The DSD was an organization that was hoarding futuristic technologies for the sake of taking over the world, and you had to stop them! The DSD was a pay-to-unlock sort of thing, that unlocked some interesting militaristic units, but that we’re only really good for defense.
The units included:
—Tank: 20 Morale
The tank is as it sounds. Big, slow, and with lots of HP. The tank basically just replaces the Paladin as the stall-against-Arblasters unit. However, the tank does deal heavy damage to the Tent if it manages to get there.
—Aircraft: 30 Morale
The Aircraft, too, is a very HP-rich unit, except that it moves very quickly and can drop up to 5 AoE bombs onto opposing units as it passes.
—Saucer: 40 Morale
The Flying Saucer is a dreadfully slow-moving disk that carries a tower on it… That’s pretty much the just of it.
The Tesla Tower shot an electric ark that hit and stunned 3 enemies at once, but for only a little less than half the damage. So about 1.3x more damage than the Firebolt, plus a stun effect, but its weakness? Less range and it sits on the path, allowing ranged units to hit it. Or you could also make it 1/3rd damage onto 3 units and set it back, and make it light a Firebolt that Stuns instead of Panics. Your choice.
The DSD was a bit different, though. Like the Dungeons, you have to beat paths of gradually increasing difficulty to unlock unit levels and Construction Plans. However, these levels were different than most. Rather than having a time limit and being able to summon units at-will, you were given a finite number of units to start (since only so many units can sneak in at once), but had no time limit. The trick, then, was in how to keep your units alive against an onslaught of incoming enemy forces. And each stage had it’s own requirements. For example, “Only you and 5 Arblasters could sneak in!” Or “You and 1 Werewolf!”
This would be difficult to implement, which is exactly why the Restricted Area would be pay-to-unlock. And since it would be pay-to-unlock, that’s why the unlockables are limited only to defensive units, not to something that could give certain players horribly unfair advantages in raiding.