If y'all have any extensions than please add them to the list as such below:
Triathlon% - 3x marathon
Quintalon% - 5x marathon
Arcade% - complete all arcade achievements
NumberPad% - get all achievements in the blue area
Talk% -Talk and get every achievement that includes all three NPC's you can talk to.
Color% - Change to every single color
NoPortalExplore% - Explore every ? but you're only allowed to use the light blue and yellow
portal (Unless you skip the yellow portal likein the AllPortal% WR)
NoGhost% - Get every achievement possible without ghosting once.
Any% - do X% Of all achievements
0% - Use the flashplayer glitch
CaryKH% - Type 3 1 18 25 11 8 in the blue area
Bubble% - Play with Shift on the entire time
The Bubble one, has 2-3 impossible achievements so i would call it Bubble% AMAAP (As Mush Achievements As Possible)