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