2 x 2 x Combo
72.1%
Get 2 x Kill Combo two times.
Area 51 Defense Achievements
9 achievements
5 x 5 Kill Streak
59.8%
Get 5 x Killstreak five times.
200 Kills
51.6%
Two hundred targets destroyed.
2000 Kills
19.6%
Two thousand enemies eliminated.
20 000 Kills
10.6%
Twenty thousand foes removed.
200 000 Kills
10.6%
Two hundred thousand adversaries decimated.
2 000 000 Kills
10.6%
Two million invaders liquified.
Airstrike Withheld
10.6%
Survive through ten waves without a single airstrike.
Health Pickups Withheld
11.4%
Survive through five waves without health power-ups.