http://store.steampowered.com/app/901553/
The King of Indie Games has reclaimed his crown with Serious Sam HD: Gold Edition. The definitive collection of Serious Sam’s trademark arcade-style shooter gameplay is packed to the brim with non-stop action and includes revamped high-definition versions of Serious Sam HD: First and Second Encounters as well as classic versions of both games!

Developed by Croteam and powered by the Serious Engine 3, Serious Sam HD combines spectacularly enhanced visuals, including more polygons, higher resolution textures and more special effects for the gold standard in arcade-style FPS gaming. Serious Sam HD: First and Second Encounter feature epic campaign co-op modes and over a dozen high-octane multiplayer modes like deathmatch, capture the flag and the new survival matches for up to 16 players.

Serious Sam HD: Gold Edition also includes the original Serious Sam: First and Second Encounter titles from 2001/2002 with four-player split screen, LAN support and the Serious Editor for custom maps creation!
Free Update - Serious Sam HD Fusion Pack

The Serious Sam HD Fusion DLC Pack combines all the campaign and multiplayer levels from Serious Sam HD: The First Encounter into Serious Sam HD: The Second Encounter for the ultimate in classic first-person shooter mayhem. For the first time ever, enjoy new modes like Beast Hunt and My Burden using the classic maps from Serious Sam HD: The First Encounter.
Key Features

SINGLE PLAYER

★ Various Environments and Secrets – Unleash mayhem on 4 different spectacular worlds: Ancient Egypt, South America, Ancient Mesopotamia and Medieval Europe. Discover hundreds of secrets scattered across the blood-soaked battlefields across both Encounters.
★ Unique Enemies and Bosses – Fight with nightmarish warriors in Mental’s army, including iconic baddies like the Beheaded Kamikaze, Syrian Werebull, Kleer Skeleton and Cucurbito the Pumpkin. Go head to head against massive bosses including Mordekai the Summoner and legendary Ugh-Zan III.
★ Special Weapons and Power-Ups – Wreak havoc with a huge arsenal of weapons like the Minigun, Rocket Launcher, Cannon, Flamethrower, Sniper and Chainsaw. Use Power-Ups to increase your fighting and agility skills to gain advantage again Mental and multiplayer opponents.

MULTIPLAYER

★ Survival Mode – Try to stay alive as long as you can against continued enemies’ attacks in specially designed survival maps!
★ Co-Op Modes – Plunge into chaos with up to 16 players in Cooperative Campaign, Survival Co-op and Coin-Op Co-op!
★ Versus Modes – Fight against your friends in versus modes including Deathmatch, Beast Hunt, Last Man Standing and My Burden!
★ Team Modes – Compete against other teams in team matches including Team Deathmatch, Capture the Flag and Last Team Standing!

STEAM FEATURES

★ Steam Achievements – Earn over 100 amazingly attractive achievements to boost your social standing and become more attractive.
★ Steam Leaderboards – See your score recorded in both single player and cooperative leaderboards.
★ Steam Cloud – Store your profile online on the Steam Cloud servers, including your bindings, last played level and campaign progress.

SERIOUS SAM CLASSIC VERSION FEATURES

★ 4-Player Split Screen – Fully supported in all game modes, in both LAN play and online!
★ LAN Support – Play multiplayer in your local network!
★ Scorematch Mode – Play versus mode for scores!
★ Multiple Gravity – Experience several gravities in one room or fight with enemies which are ambushing you from the ceiling, while you jump up to confront them!
★ Serious Tools – Includes tools used to create the game, Serious Editor and Serious Modeler, so gamers can create their own levels!
★ Runs on both old and new PCs – Can be played on most current and older PC video cards