When It Hits the Fan achievements

Complete City - Stage 1

Defeat the alien zone boss

Defeat the city zone boss

Destory all alien spaceships in Hell Stage 3

Kill the third boss without killing any lava spitters on Normal mode or higher

Unlock the laser cannon in Mothership Stage 1

Kill the second boss without dying on Normal mode or higher

Survive the hard route in City Stage 2 without dying

Unlock the laser cannon in Lab Stage 2

Defeat the hell zone boss

Kill the first boss without killing either turret on the tank on Normal mode or higher

Kill 15 enemies with one blast of the laser pistol