The Gunstack is an item and gameplay concept in Serious Sam: Double D.
The Gunstack is an item the player makes out of weapons and Gunstack Connectors. A Gunstack lets the player create a stack of up to six weapons that will fire at once when the player hits the fire key. They will also continue firing as long as the player hold the fire key down. There are no “invalid” combinations, so the player is free to make a Gunstack however they feel.
Gunstacks can be customized at any time by hitting Q or selecting it in the menu. Up to eight Gunstacks can be created.
Both weapons and Gunstack Connectors are often found in secrets, so the player needs to explore often if they wish to do things such as built multiple powerful Gunstacks or create a Gunstack for a certain situation.
- Making Gunstacks for certain situations is a very good idea. For example, if the player needs to go fight off enemies with a lot of health, such as the Caterfighter, the player can take out a Gunstack filled with powerful weapons such as the LM32 Rocket Launcher and MadDog Grenade Launcher. Then, once the strong monsters are dead and then enters a tight tunnel with enemies in it, the player can switch to a more close-quarters focused Gunstack that has weapons such as the 0-4377 Flamethrower or Insane-brand Chainsaw.
- The modular nature of the Gunstack lets the player create combinations that may not seem obvious at first. For example, a 0-4377 Flamethrower can be attached near the top of a Gunstack and used to destroy enemy projectiles before they can reach the player, or an Insane-brand Chainsaw can be stuck somewhere to deal with enemies in close quarters that manage to survive the attacks from other weapons.
- Try to match the weapons in a Gunstack for the situation they are built for. For example, don't put an LM32 Rocket Launcher in a Gunstack meant for close quarters, or try to put an Insane-brand Chainsaw or Type II Machine Pistol in a stack that's built to have the most powerful ranged weapons in it.
- Weapons that are near the top of a Gunstack may not work as expected in a location that has a low ceiling. If a Thompson Submachine Gun is pointed at or clips through a ceiling, it's bullets will just hit the wall and do nothing. Explosive weapons are a bit more dangerous in this situation, as their projectiles will explode as soon as the fire key is hit if they're clipping through a wall or facing the edge of it.