Here is the full list of all 40 Indie Game Battle achievements.
Win a match as Cal.
Win a match as Teslakid.
Win a match as Gontaper.
Win a match as Sol.
Play a match in Turbo Mode.
Win a match as Goat.
Win a match as Dust.
Win a match as Pico.
Win a match as Captain Viridian.
Win a match as Zee Tee.
Win a match as Red Drop.
Win a match as NoLegs.
Win a match as Woodle Tree.
Win a match as Electroman.
Win a match as The Kid.
Win a match as Artist.
Get 100 total KOs.
Win a match as Gip.
Win a match as Chip.
Win a match as Huey.
Win a match as Adventure Pals.
Win a match as Max & STEVE.
Win a match as Bingo.
Win a match as Jarvis.
Win a match as Wizard.
Win a match as Aria.
Win a match as Poncho.
Win a match as Matt.
Win a match as Rex.
Win a match as Salad Fingers.
Get 10 total KOs!
Win your first Survival match.
Win a match as Blue Blob.
Launch the game for the first time.
Get 500 total KOs.
Get 1000 total KOs.
Get 5000 total KOs.
Get 10000 total KOs.
Get 50000 total KOs.
Get 99999 total KOs. Wow, you deserve a cookie for this one.