Here is the full list of all 20 Globat Pixels achievements.
Kill 5 enemies in one life with the bouncer
Change weapons 12 times in one life
Win against AI with maximum difficulty level
Win against AI with maximum difficulty level whilst only using the bouncer
Kill 2 enemies with one shot
Score the last point whilst playing with an ally
Die 15 times in one game and still win the game
Change weapons 12 times in one game
Kill 7 enemies in one life with the homing bullet
Kill 3 enemies in one life with the particle ray
Play the Eiffel tower map
Play the Taj Mahal map
Survive 40 seconds without shooting
Kill 5 enemies in one life
Kill an enemy with the homing bullet
Use 4 weapons in one game
Kill 3 enemies with one shot
Kill an enemy with the shotgun
Kill an enemy with the particle ray
Kill an enemy with the bouncer