Here is the full list of all 23 GAUGE achievements.
Score 2.000.000.000 points in hard mode.
Score 1.000.000.000 points in hard mode.
35.000.000.000
28.000.000.000
Get 100 bonuses in one game.
Score 20.000.000.000 points without using second gauge.
Score 10.000.000.000 points without using second gauge.
Score 1.500.000.000 points in time mode.
Score 600.000.000 points in time mode.
Unlock 15 life extensions.
Score 2.500.000.000 points in touch mode.
Score 1.000.000.000 points in touch mode.
Play 1200 seconds straight.
20.000.000.000
Error#14.000.000.000#!$)^(=_001'*!
Press the spacebar 5000 times in one game.
----- 10.000.000.000 -----
Get 50 lives.
Meow 6.000.000.000 Meow meow meow.
Score 2.000.000.000 points in limitless mode.
Cheat code activated.
Play 90 seconds with 2 gauges.
This achievement is here to prevent you from filling achievement gauge to 100%... and die. You can't unlock it.