Here is the full list of all 26 MegaBlasters! achievements.
Win a 4 blaster match without getting hit
Win your first match
Win atleast once in every single map
Win 3 matches in a row
Win 5 matches in a row
Win 7 matches in a row
Win 10 matches in a row
Win a total of 250 matches
Win a total of 500 matches
Get a kill with 1 health point
Kill all other blasters in a 4 blaster match
Kill all other blasters in a 4 blaster match without taking damage
Kill another blaster by punching them
Kill another blaster while you're both in the air
Kill a total of 500 blasters
Kill a total of 1000 blasters
Say gg in the in-game chat
Use the in-game chat atleast once
Touch the sky of an open map
Look at another blaster for atleast 10 seconds
Destroy a destructible structure with a gun
Jump boost into the air with a shotgun
Stay in the air for atleast 45 seconds using the flying gun
Cause 100 explosions
Get hit by a car
Make another blaster get sucked into a blackhole you created