Serious Sam: Next Encounter is a first person shooter that takes place in Ancient Rome, China, and Atlantis. Gameplay is much like other games in the Serious Sam series. The goal is to reach the end of the level while fighting off huge hordes of enemies. Weapons and ammo are scattered throughout the levels in order to make sure that the player has the weapons and ammo needed to reach the end of the level, along with healing items to recover lost health and armor in order to reduce the amount of damage the player takes per hit. The player can also use vehicles in certain levels, making it the first Serious Sam game that lets the player drive around in vehicles.
Surprisingly little has been lost gameplay-wise, even though the game is built for a system weaker than the PCs that The First and Second Encounters were made for. There are still large enemy hordes, and levels appear to be the largest ones ever seen in a Serious Sam game. There is only a bit of slowdown, but only when there are a lot of enemies on-screen at once. Graphics had been scaled down to make all the content fit, so they aren't as good as the graphics in the original game, but they aren't terrible either.
However, unlike other Serious Sam games, there is a more noticeable emphasis on points. In previous games and future games, points are there for fun and there's nothing that can really affect one's score outside of a power up. Next Encounter is a bit different for several reasons. First, there is game mechanic called “Super Combo Killing Spree” that gives the player a speed boost and doubles the amount of points they get for around 10 or so seconds. It is obtained by killing 20 enemies as long as there is a “Combo x” indicator on the screen. If this indicator disappears, the player's kill count is reset.
Next Encounter comes with several game modes. It contains the usual single player, co-op, death-match, but also has two new modes; Hold the Flag and Pass the Bomb. Two people can play co-op, while four can play death-match and death-match-based modes.
Unlike other PS2 games, Next Encounter allows the player to play online. The online services are still working. However, it cannot be played online with the Gamecube.
Serious Sam: Next Encounter starts out with Mental talking to an Evil Serious Sam Clone and telling him not to do anything bad nor get into Mental's Time-Lock while he's gone. However, a short while after Mental leaves, the Clone decided to jump into the Time-Lock. Soon afterwards Sam and a scientist are investigating an unusual time anomaly in a lab. It's determined that Sam should enter a Time-Lock and investigate the anomaly himself.
Sam teleports into the Colosseum in Ancient Rome. After appearing and clearing out some of the Evil Clone's forces, a glitch in the Time-Lock warps Sam far away from the Colosseum. Sam, still determined to figure out what's going on, fights through the Roman countryside and ends up in Rome. He carves a path through the enemy forces until he manages to reach the Colosseum again. After being tricked into giving some of his money to a stand made by the Evil Clone and seeing the large amount of enemy forces that are in the Colosseum, Sam decides to sneak into it via the sewers. After a rather nasty trip through the sewers, Sam is finally back to where he started. However, the Evil Clone is more prepared this time, and sends out stronger monsters at Sam. Finally, he brings out his big guns, a gigantic creature named the Diablotaur. Sam defeats the creature, which also shuts down the time anomaly noted at the start of the game. However, the Evil Clone escapes into another time period.
After defeating the Diablotaur Sam is warped to Ancient China via the Timelock. Again, there appears to be strange anomalies in this time era. These “anomalies” soon turn out to be more of Mental's forces, most likely left by the Evil Clone. Sam travels through some of China's countryside and enters some old buildings located in the area. Sam then found out that there was another Time-Lock in an old pagota, which was also the source of the time anomaly that NETRICSA detected when Sam first warped to Ancient China. Much like in Ancient Rome, Sam forged a path to the old pagota, traveling through castles and a village along the way. Finally, Sam reached the pagota. What he found was a very, very large room underneath. However, before Sam could figure out what was going on, the Subterranean Hydra Emperor burst through the parts of the floor. It was clear that it was the source of the anomaly, as it seems to have been altered by Mental for his own purposes. Sam managed to defeat the Emperor, which cleared up the time anomaly and revealed the Time-Lock NETRISCA detected earlier.
After going through the Time-Lock, Sam appears near the lost city of Atlantis. Things start becoming more clear while Sam starts traveling though the icy landscape that leads to Atlantis; the Atlanteans had a connection to the Sirians, but the connection was still not clear at the time. Finally, Sam managed to enter Atlantis, and saw that every living thing in the city had become soldiers for Mental. Sam then fought through Atlantis in order to see what was the cause of the time anomaly. Near the other side of the city, NETRICSA discovered that there was an old Sirian ship buried underneath the city; more specifically, the throne room for Atlantis' royalty. Sam then boarded a sub supplied to him in order to get deeper into the city.
After getting to the deeper parts of the city, he managed to enter the areas meant for royalty. However, there were several security measures meant to prevent intruders from entering the city, such as a strange void with four triangle-shaped platforms, a gravity system that was damaged, and a set of three mini-Timelocks that had to be cleared of monsters in order to activate the teleport to the throne room. These challenges, along with the monsters that were scattered throughout them, were quite a challenge, but Sam managed to overcome them. After bypassing all of the security systems, Sam finally managed to enter the throne room, which was heavily guarded by Mental's forces. Sam killed them all and managed to enter to get a chance to sit on the king of Atlantis' throne. After relaxing in it for a minute or two, along with a group of cheerleads cheering him on for being so great for “finishing” the game, the throne became a trap door and sent Sam flying down into the Sirian spaceship.
Finally, Sam managed to enter the Sirian ship, and NETRICSA was detecting a huge anomaly in it. The ship was infested with Mental's hordes, showing that Mental was very interested in something in the ship. Sam fought through the ship, and managed to get somewhat close to the core. Thankfully, there was a Gnaar with a taxi nearby, so he hitched a ride with the Gnaar to the core. When Sam reached the core, everything became clear; the Evil Clone's goal was to find and reactivate an old Sirian defense system built into every Sirian spaceship called the Sirian Darklord. The Darklord is a very powerful mech that was nearly indestructible because of it's powerful shields and ability to use the ship's materials in order to rebuild any damaged limbs. However, NETRISCA discovered that there was a few moments when the Darklord was vulnerable to attacks.
After destroying the Darklord, Sam walked to the remains of it's head, where suddenly the Evil Clone popped out of it. It seems that the Evil Clone was the one true mastermind behind everything that Sam went though, and that Mental really was off doing something else. After spanking the Evil Clone, Sam decided to take it back to the present with him. However, the teleport sequence was rigged to create more Evil Clones when it was activated. After Sam and the Evil Clone warped back to the present, the new clones were created, ready to do more mischief.
"The end?" It says in hovering text when the final cut-scene finishes.
Ancient Rome: Incident at the Arena
Ancient Rome: Senator Cicero's Villa
Ancient Rome: The Senator's Vineyards
Ancient Rome: Via Aurelia
Ancient Rome: Opening the Aurelian Gates
Ancient Rome: Temple of Neptune
Ancient Rome: Through the Servian Gate
Ancient Rome: Temple of Mars
Ancient Rome: Emperor's Garden
Ancient Rome: Caesar's Palace
Ancient Rome: Touts at the Colosseum
Ancient Rome: Under the Colosseum
Ancient Rome: Showdown at the Arena
Feudal China: Splashdown in Xifengkou
Feudal China: The Monkeys of Juyongguan
Feudal China: Jiayuguan Fortress
Feudal China: Dunhuang Oasis
Feudal China: Magao Caves
Feudal China: Cave of the Wickerman
Feudal China: The Three Halls of Harmony
Feudal China: Yuhuayuan - Imperial Garden
Feudal China: The Beast Beneath the Palace
Legendary Atlantis: A Chilly Reception
Legendary Atlantis: Temple of Steam
Legendary Atlantis: The Deep City
Legendary Atlantis: The Guardian Gates
Legendary Atlantis: The Halls of Translation
Legendary Atlantis: The Tower of Confusion
Legendary Atlantis: The Halls of Transposition
Legendary Atlantis: Ascending the Throne
Legendary Atlantis: Sirian Mothership
Legendary Atlantis: Engine Core Critical
Ancient Rome (Extra): Praetorian Camp
Ancient Rome (Extra): The Forum Romanum
Ancient Rome (Extra): The Forum of Trajan
Ancient Rome (Extra): Addressing the Senate
Ancient Rome (Extra): Caesar's Sanctum
Feudal China (Extra): The Silk Road
Feudal China (Extra): The Gate of Supreme Harmony
Legendary Atlantis (Extra): The Steam Tower
Legendary Atlantis (Extra): The Geothermal Tunnels
Legendary Atlantis (Extra): The Corridors of Power