Here is the full list of all 28 Exertus achievements.
Use the Rocket Jump 150 times.
Use the Rocket Jump 50 times.
Restart 100 times.
Play Speedrun Mode.
Complete level #5 from the Night collection.
Begin the Night collection.
Jump 1000 times.
Complete level #10 from the Inertia collection.
Begin the Inertia collection.
Complete level #27.
Use a horizontal platform in an official level.
Land on the beam of a spinner.
Use the quick turn mechanic.
Hit 1500u/s after wallrunning.
Restart 10 times.
Hit 50 bunnyhops in official levels.
Use an elevator in an official level.
Complete level #1.
Jump 100 times.
Complete Tutorial level.
Wallrun in an official level.
Have a look around the playground.
Use the impulse fire to rocket jump.
Land on a gravity booster in an official level.
Use double jump in an official level.
Perform a slide successfully in an official level.
Run into lasers in an official level.
Begin Tutorial level.