Annihilation

Get a "Perfect" rating on Stage 1. (Survive all 10 waves without losing any base health)

Get a "Perfect" rating on Stage 3. (Survive all 10 waves without losing any base health)

Kill 10 enemies in a row without missing a shot. (Single Player)

Kill 20 enemies in a row without missing a shot. (Single Player)

Kill 40 enemies in a row without missing a shot. (Single Player)

Annihilate 1 enemy. (Single Player)

Annihilate 500 enemies. (Single Player)

Use a Spike Strip Item. (Single Player)

Use an Upgraded Spike Strip Item. (Single Player)

Use an Auto Turret item. (Single Player)

Use an Upgraded Auto Turret item. (Single Player)

Grab a health buff. (Single Player)

Grab a speed buff. (Single Player)

Grab a damage buff. (Single Player)

Kill an enemy with an upgraded bullet. (Single Player)

Kill an enemy with a laser bullet. (Single Player)

Purchase the extra pistol upgrade. (Single Player)

Have more than $2,500 at one time. (Single Player)

Kill an enemy by running into it. (Single Player)

Get a highscore of 300 or higher on Stage 1. (Single Player)

Get a highscore of 850 or higher on Stage 3. (Single Player)