Research

Other than ranking up, research is another way to unlock things, it does so in an interesting way.

First, to research something click on the research lab in the icon you want to research (Make sure it's bright green, I'll get onto that later), hovering over the icon will show description for it, the cost (Highlighted red if you can't afford it) and, if you haven't researched the above tier, "To find out about this project, research the above one first!"

To unlock one thing research all others linked to it above.

Colours
Bright green - Researched

Slightly darker green - Researching

Bright grey - Unlocked

Dark grey - Not unlocked

Research points
To research stuff, it requires research points to research (Then you need to wait a bit, do something with that time)

You may get research points from completing a track with 3 different types of towers (Just towers that behave differently to others in even the slightest sense of way, nothing more) the reward varies between track difficultly and difficulty in general.

General difficulties
On easy you get 75% the base reward (Minimum of 1 less than the base reward)

On medium you get the base reward

On hard you get 150% the base reward (Minimum of 1 more than the base reward)

On impoppable you get twice the base reward

On CHIMPS you get three times the base reward

Track difficulties
Below beginner - 1 RP (Research point(s))

Beginner - 2 RP

Intermediate - 3 RP

Somewhat tricky - 4 RP

Advanced - 5 RP

Expert - 7 RP

Extreme - 10 RP

Devastating master - 12 RP

Nearly impossible - 15 RP

Good lucky - 20 RP

Uber beyond crazy beginner - 0 RP

Trivia
This may refer to a lot of games that use research (Mainly idle games)