Achievements are given to teams for completing various arbitrary tasks. Often times, they are created at the spur of the moment throughout the day of the event in order to award teams for doing something particularly funny or noteworthy.

First StepsYou solved your first puzzle.
Challenge InitiateYou completed 5 challenges.
Challenge JourneymanYou completed 10 challenges.
Challenge AdeptYou completed 15 challenges.
Challenge MasterYou completed all 20 challenges.
SesquipedalianYou correctly entered a very long partial answer.
SesquipedelianYou incorrectly entered a very long answer - check your spelling!
Shut Up And Call GCYour guesses don't make sense to me, so just (oo-oo-ooh) shut up and call GC.
One Too Many Turns of the Time TurnerUsed a team name related to a past year.
Know Your CalendarSign your waivers with the correct date the first time.
Opening ActYou were on time for your assigned opening time.
The TruthYou learned the Necromancer's identity.
Closing the LoopYou met Edwin.
The Prophecy of the DeadYou visited the Celebration of the Celestial Alignment and learned the real stakes.
Wheels Within WheelsYou met Gemini.
Finished the Game 2019You finished The Prophecy of the Dead.
Not Invisible From The LawYou had a run-in with the police.
ApimancyYou had an encounter with bees.
ClairvoyantYou only needed to submit one slip to Zoltar.
Un-familiarChester performed a magic trick for staff.
Eat Your WordsAccidentally ate the answer on Dubble Bubble (we're sorry ... this was definitely not expected or intentional).
Hare ModelYou provided your own clothes or accessories for your familiar.
Marcana NaturalistHelped clean up a puzzle site, preserving the natural order. (Thanks! =100x)
Dictionary AttackGot the final answer to Elements without solving the system of equations.
The Dubble Bubble Bubble Gum is DispleasedYou removed your blindfold during Dubble Bubble.
GluttonyYou ate a lot of candy at Dubble Bubble.
Team is WinYou tried to create a WIN at The Bizarre.
BlasphemyYou tried to create GOD at The Bizarre.
Destroyer of WordsYou undid more scarves than necessary.
Nothing Up My Sleeve...You performed a magic trick of your own.
Salt and PotatoYou submitted "Prongles" as the answer to Interconnected
PronglesYou submitted "That's Great" as the answer to Interconnected
Master SurgeonYou removed the clue from Chester with minimal damage.
You MonsterYou needlessly dismembered your familiar.