Unlock the Sniper.

Unlock the Rocketeer.

Have the Gunner kill 500 zombies.

Have the Sniper kill 500 zombies.

Have the Rocketeer kill 500 zombies.

Have the Gunner shoot 1000 bullets.

Have the Sniper shoot 750 bullets.

Have the Rocketeer shoot 500 rockets.

Have the Gunner stun 200 zombies.

Have the Sniper shoot through 100 zombies.

Have the Rocketeer shoot 50 extra rockets.

Use Bomb of Duty 50 times.

Use Time Machine 35 times.

Use Air Strike 20 times.

Rescue 15 refugees in total.

Acquire all gems.

Kill 100 giant zombies.

Kill 100 flying zombies.

Kill 1500 zombies in total.

Have 500 critical shots in total.

Defeat Zombogod.

Defeat Zombogod with perfect life.

Have 10000 gold.

Fully upgrade all characters.