Kill three enemies with one explosion five times

Finish the game in Hard Mode

Find all 60 treasures

Kill 20 enemies with the Desert - 5

Find the Strange Relic

Finish the game in Easy Mode

Kill three enemies with one explosion

Kill 50 enemies with the M4

Find 45 treasures

Find 35 treasures

Kill 20 enemies with the Wes - 44

Kill 30 enemies with the M79