Here is the full list of all 70 Serious Sam HD: The Second Encounter achievements.
Accumulate a total of 100,001 enemy kills and frags combined.
Win 1000 Deathmatch games.
Win 100 deathmatch games.
Win 25 1-on-1 Deathmatches.
Complete 100 Deathmatches.
Earn gold medals on all Survival levels in cooperative Survival.
Frag 100 different players.
Win 100 My Burden matches with at least 3 players.
Frag a total of 1337 players.
Win 100 Last Man Standing matches with at least 4 players.
Frag a total of 1000 players.
Win one round in Last Man Standing game with at least 4 players.
Win one My Burden match with at least 3 players.
Frag 10 players without being killed in at least 4 player Instant Kill match.
Make at least 3 kills in one Instant Kill match.
Win 100 Instant Kill matches.
Win a Beast Hunt match on all game levels.
Win a Beast Hunt match on any level.
Score a total of 100 points in CTF matches.
Complete a Deathmatch with frag limit set to at least 200. (Frag limit must be reached!)
Win a Deathmatch Marathon.
Frag a total of 500 players.
Kill 50 Syrian Werebulls with a knife.
Complete the game in single player on serious difficulty.
Complete the game in single player by beating estimated time on each level.
Complete The Grand Cathedral level on serious difficulty without dying or loading.
Deliver the final blow to Mordekai with the Knife.
Find all secrets in single player.
Perform 100 rocket jumps.
Find at least 80 secrets in single player.
Win a Team Beast Hunt match on all game levels with least 2 players on each team.
Win a Team Beast Hunt match on any level with least 2 players on each team.
Find all 3 Cannons in Teotihuacan - The City of the Gods.
Win 100 Last Team Standing matches with at least 2 players on each team.
Earn a round for your team in Last Team Standing game with at least 2 players on each team.
Win 100 Team Deathmatches with at least 2 players on each team.
Win a Deathmatch.
Win an at least 4 player Deathmatch by reaching frag limit of at least 25 without dying.
Frag 100 players in a knife-to-knife fight.
Win 25 CTF matches with at least 2 players on each team.
Win a CTF match with at least 2 players on each team.
Hold the Burden for at least 10 minutes in My Burden match with at least 3 players.
Frag 100 players with a knife from behind.
Frag 25 players with a knife while having no more than 10 health left.
Kill 100 Harpies with the Sniper rifle.
Complete any level in single player.
Find a secret under water.
Earn gold medals on all Survival levels in single player Survival.
Earn at least a bronze medal on any level in single player Survival.
Kill 1000 enemies with the Laser gun.
Kill 300 Kleers with the Cannon.
Win one Team Deathmatch with at least 2 players on each team.
Complete the game.
Complete a Coin-op cooperative game on normal or higher difficulty.
Pick up at least 10 extra life items in Cooperative Coin-op game.
Complete the Persia episode in single player or cooperative.
Pick up 100 gold coins in Coin-op Cooperative game.
Burn 500 enemies to death.
Complete the Medieval episode in single player or cooperative.
Complete the South America episode in single player or cooperative.
Complete any level in at least 3 player cooperative game.
Get all 3 Rocket launchers in Palenque - Sierra de Chiapas.
Earn at least a bronze medal on any level in cooperative Survival.
Frag all players in a single frag combo.
Frag the same player 10 times during a single round in at least 4 player match.
Frag 100 players with a knife.
Frag the same player 5 times in a row in at least 4 player match.
Perform 4 frags with each being no more than 10 seconds apart from the previous frag in at least 4 player Deathmatch.
Frag a total of 100 players.
Complete a deathmatch game with at least 1 frag.