
Unlike other vehicles, mechs cannot be exited once entered.Īn unknown amount of time before the events of Serious Sam 3: BFE, a massive portal opens in Tunguska, Russia which serves as a bridgehead for Mental's forces to invade Earth. Players can also pilot multiple mechs that appear throughout the game, which are armed with machine guns and rocket launchers. Vehicles play a larger part in the game than other entries, as multiple levels have the player use vehicles to traverse some environments. Another addition are weapon mods, which unlock alternate fire modes for certain weapons. Gadgets are smaller items which range from support items that can induce temporary buffs to the player to offensive ones such as crystallised black holes that suck up all enemies nearby. Side quests are optional objectives that reward the player with items and weapons. Only 10 S.A.Ms are present within the game, making it impossible to fill out the tree in a playthrough, and as such the player can unlearn a skill, restoring the point and losing the benefits of the skill. The skill tree, which is progressed by finding objects called Syrian Artefacts of Might (S.A.Ms), can enable multiple skills such as dual wielding any weapon, riding enemies or using signs as weapons. Many new additions are present in Serious Sam 4, mainly a skill tree, side quests and gadgets.

The knife from the Encounters returns, replacing the sledgehammer.

Reloading returns from Serious Sam 3: BFE, but the weapons have been adjusted, making this less of a necessity. The player does not have a weapon limit, and is able to carry an infinite amount, such as shotguns, a minigun, grenade launcher and sniper. Enemies either attack close range or from a distance. As in other entries in the series, Serious Sam 4 involves fighting against massive hordes of enemies in large areas.
