Serious Sam HD: The First Encounter achievements

Frag 25 players with a knife while having no more than 10 health left.

Complete a deathmatch with frag limit set to at least 200. (Frag limit must be reached!)

Frag 100 players with a knife from behind.

Complete a co-op game on serious difficulty and extra enemy strength on 400%.

Complete Metropolis level in single player on serious difficulty without loading.

Frag 100 players with a knife.

Frag the same player 5 times in a row in at least 4 player deathmatch.

Kill all enemies in Karnak in single player.

Frag all players in a single frag combo.

Complete the game in single player on serious difficulty.

Complete The Great Pyramid in co-op with blood option set to hippy.

Complete the game in single player without firing a single bullet or shell.