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