RBE stands for "Red Bloon Equivalent". It's the number of total red pops the wave will take total to defeat (and the number of potential lives lost if you let the wave get through).
Note that it doesn't change in any way to distinguish, say, lead or camo bloons from the others. It's just a slight tool for estimation.
I have to say that this game was enjoyable for a bit, but felt very easy and very repetitive. There's no real reason not to attack cities whenever the option presents itself, because you'll recoup the fame loss quickly. There's no motivation to keep old units you've trained instead of trading them for new unique units, the unique units tend to be better than or on par with mundane units two levels above them. You can't give your troops any system of tactics, so it's basically "healer, two blockers and ranged". It seemed very... Flawed. Pretty, but not much substance to it.
Just my thoughts.
Something I forgot to mention on the Mega Tower I brought up: It's not just fast. The damage stat is 357 (It one-hits stuff for a ridiculous amount of waves), and it's range is enough that if it's on the center x or center y axis (preferably both) it can hit the entire map.
Anyone looking for a good combo for a Mega Tower should try out a max fire rate, max machine gun, max splash damage, and max anti ghost. It has a reload stat of "2" when it's done, so it's basically a line of bubbles. Probably should count as cheating. I'm gonna try to figure out what a Mega Mega Tower of four of them does.
Jakeydays: Remember that you can double jump in adolescent. The only real purpose for it is to get that torch in the basement. Double jump, then bite as you fall. Should only take one or two tries.
@Snaggles: Same.
As for the game... Well, it was good. Same kind of idea as "You have to burn the rope". I don't know which came first, don't want to check, and am willing to give whichever came second the benefit of the doubt. As it is, I only rate the game as 3/5. Docked 1 for poor graphics, and 1 for it being short.
It works, it's got a nice enough layout, and it can be beaten (even though it *is* hard). 4/5, not because it's done poorly, but because it's not a stellar concept to start with. For what it is, though, it's done beautifully.
Bloons TD 5
The King's League
Bubble Tanks Tower Defense
How to Raise a Dragon
CubeField
Bloons Tower Defense 2
Nano War
You Only Live Once
Red Remover
WalkRight
Little Wheel
The Multiplication Game