Here is the full list of all 25 RUSH achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Place a sign on every square of the credits level
Complete all hidden levels
Find all hidden levels
Make 6 collisions at the same time
Create a conveyor belt of 10 signs
Complete all actual challenge levels
Actually solve level garlic
Find the hidden Toki Tori statue
Create an endless loop in a level using a conveyor
Create an endless loop in a Medium level
Create an endless loop in a Hard level
Create an endless loop in a level using a telewarp
Find a hidden level
Complete all hard levels
Create an endless loop in an Easy level
Lead 1111 cubes to their exits
Create an endless loop in a level using two directional signs
Deliver all presents in the eight levels when they are touched by frost in December
Complete all medium levels
Solve a level different from how the hint system suggests
Complete a level with signs to spare
Complete the Solar Flare level
Complete all easy levels
Fail a level 15 times in a row
Complete all tutorial levels