Here is the full list of all 26 BIT.TRIP RUNNER achievements.
Complete Triumph
BURGER MOUTH
Complete The Gauntlet
Find 3 friends and beat the challenges they are in
Repel 100 Beats
Complete Tenacity
Get Bonked by a monster
Catch a fish!
Complete Impetus
Complete Odyssey
Collect 1,000 Gold Bars
Jump 1,000 times
Bonk after missing a Gold Bar to rewind time and try again
Roast your mallows over a campfire
Get CommanderVideo's cape
Complete a bonus challenge
Register a high score on the leaderboards
Get a PERFECT score in all Impetus Challenges
Get a PERFECT score in all Tenacity Challenges
Get a PERFECT score in all Triumph Challenges
Complete a level in one sitting
Get the Game Over
Get a PERFECT in all challenges
Watch the hidden cutscene
Get a PERFECT on one challenge
Beat all challenges on Perfect difficulty