Forth to the past
Complete the first Egypt level.
There can be only one!
Kill the Highlander in Valley of the Kings.
With our powers combined
All Elementals acquired.
The talk of parties
Defeat the giant lava golem.
No Fridge to Hide
Obtain the Crystal Skull.
A message to the stars
Find the rising obelisk.
Going with the Wind
Kill the boss and complete the South America episode.
Friendly First Encounter
Finish The First Encounter in cooperative.
Million Funerals and No Wedding
Kill the boss and complete the Medieval episode.
Change of scenery
Find Moon Mountains.
Once Upon a Time in Babylon
Kill the boss and complete the Persia episode.
Yes, I'd like to kill more monsters
Find Sacred Yards.
Kill an enemy player while you're dead.
Deal a total of 1 million damage to enemies.
The Good, the Bad and the Enormous
Finish The First Encounter on single player.
Find a secret Plasmathrower in The Second Encounter.
Friendly Second Encounter
Finish The Second Encounter in cooperative.
Stuff of Legends
Find the XL4P Beam Gun outside of Bright Island.
This achievement is impossible to get.
The Second Encounter
Finish The Second Encounter on single player.
Using explosive weapons, kill 10 people in a row.
There used to be an alligator pit here
Unfortunately, we don't have the right model for it, so this'll do.
In a match of at least 6 players, run 2 kilometers without getting killed.
Find a secret bouncing rock.
Newton's worst enemy
Mess with the gravity for a total of 60 minutes.
Find a secret Minelayer in The Second Encounter.
That all you got?
Finish the first level of The Second Encounter taking no damage in at least normal difficulty.
Jumping is overrated
Finish the first level of The Second Encounter without jumping in at least normal difficulty.
Find and kill a Serious Sam developer in versus multiplayer.
Too Serious for weapons
Complete a level in The Second Encounter using only the knife on at least normal difficulty.
Who needs kills, anyway?
Kill less than 8 enemies on the first level of The Second Encounter in at least normal difficulty.
Kill 500 people.
Kill 5000 marsh-hoppers with the chainsaw.
Guns are seriously useless
Finish 2 levels in The Second Encounter using only the knife in at least normal difficulty.
Sam I Am
Kill 100.001 enemies.
Kill 100 monsters with mines.
Friendly Mine Trap
Kill 50 players with mines.
I am Ugh-Zan
In singleplayer, beat the last level of The First Encounter or the last level in The Second Encounter in the "I am Ugh-Zan" difficulty.
Get the gold medal on the Christmas 2014 survival level.