Destroy at least one boss alien.

Earn at least one silver medal.

Fire the orbital laser.

Survive 100 waves on the Grinder challenge mode.

Earn at least one gold medal.

Complete the Story mode.

Earn a silver medal on all missions in the Story mode.

Earn a gold medal on all Challenge modes.

Destroy 1000 aliens.

Build every tower and upgrade.

Earn a gold medal on all missions in the Story mode.

Win mission with the last core less than 10 seconds away from the map exit.

Sell 10 towers in a single mission.

Beat an advanced mission with zero cores captured.

Save a core less than 10 seconds away from the map exit.

Recover a loose core.

Witness 1 core handed off 10 times within 20 seconds.

Gain 10000 resources from interest in a single mission.

Build 6 towers within 10 seconds.

Alien time until exit exceeds 5 minutes.

No towers sold in a single mission.

Kill an alien carrying a power core.

Build all tower types in one mission.

Build all upgrades of all tower types in one mission.

Kill 1 alien.

Kill 100 aliens.

Kill 10,000 aliens.

Kill 50,000 aliens.

Win with 1,000 resources remaining.

Win with 5,000 resources remaining.

Win with 10,000 resources remaining.

Sell 5 towers.

Activate reconnaissance system.

Build 5 Gun towers.

Build 5 Inferno towers.

Build 5 Laser towers.

Build 5 Temporal towers.

Build 5 Meteor towers.

Build 5 Tesla towers.

Build 5 Cannon towers.

Build 5 Missile towers.

Build 5 Command towers.

Build 5 Concussion towers.

Beat an advanced mission with only Gun towers.

Beat an advanced mission with only Inferno towers.

Beat an advanced mission with only Cannon towers.

Beat an advanced mission with only level 1 towers.

Beat an advanced mission with only level 3 towers and no selling.

Upgrade a tower.

Inspect 10 aliens.

Use speed up controls for a total of 30 seconds in any one mission.

Reload an earlier save checkpoint.

Shoot down a flying alien.

Shoot down flying alien carrying a core.

Finish the first 3 missions.

Build 20 towers in one mission.

Build 50 towers in one mission.