The Combat Design of Signal Decay《拯救世界特别小队》的战斗设计

Signal Decay is a tactical twin-stick shooter in stealth disguise. It is a distinct game with small numbers, that is, all the enemies’s health points and the count of them are small integers. It brings a distinct experience to the game. I would call it emergent problem-solving by teamwork. To enhance the co-op experience in game, Signal Decay emphasizes on tactics and de-emphasizes on long-term strategy to some degree. To describe it, it’s more like multiple players explore the map and get through a series of hard check-point with planning and reflex. The long-term strategy is supported by a dynamic alert level mechanic in game.

See the official wiki for specific designs.

《拯救世界特别小队》(_Signal Decay_)是一个带着潜入玩法外衣的战术射击游戏。它是一个与众不同的“小数值”游戏,即敌人的血量和数目和玩家造成伤害都非常小的整数,这给游戏带来了非常特别的体验,我将它称为以团队合作进行的涌现的难题解决(emergent problem-solving by teamwork)。为了强化游戏中的合作体验,_Signal Decay_ 的游戏体验非常强调战术性而在一定程度上弱化了战略性,游戏体验类似于多名玩家通过探索并运用智慧和技巧通过一系列硬检查点的过程。游戏的战略性主要是通过动态的警戒等级实现的。

关于游戏的具体设计,可以参考官方英文 wiki

Guard 守卫

Signal Decay has many kinds of enemies and traps. The compositions of them present emergent challenges to the players. The most common enemies are guards. Although guards have similar AI, they still become different challenges with different weapons and armors, which are countered by different player weapons and gadgets.


The core combat gameplay is shooting-from-behand – one player plays as a decoy to lure the guard, and the other can shoot him from behind. A guard has two armors in the front, so he can be killed by 3 shots from front and 1 shot from behind. When a player is found and faced by a guard, she becomes vulnerable and weak. Because the guard will be always faced to the player, which makes the player hard to fight against him. The player in this situation requires the help from the other player – a shot from behind. The co-op experience is all about caring about the other and nobody being left behind, instead of fighting as an individual without coordinations. The final result is the weaker player determines how far the team will go, similar to Heroes of the Storm, Overwatch (and Dota is the opposite).

游戏的战术玩法主要围绕着背后射击的机制设计——一个玩家扮演诱饵,一个玩家可以从背后射击守卫。守卫前面有两格护甲,需要三发子弹才能消灭,而后背只需要一发。当玩家被守卫发现时,就会变为极为弱势的状态,因为守卫会永远面对玩家,对该玩家来说是很难对抗的状态,而此时需要另外一个玩家从背后一击瞬间消灭守卫。游戏的合作设计是围绕着每个人都要时刻在乎彼此,没有人会被抛在后面,而不是仅仅在同一个空间各自活动的理念设计的。最终的效果就是玩家团队中较弱的玩家决定了团队中能够达到的水平上限,这一点可以类比《风暴英雄》《守望先锋》(而 Dota 则与之相反)。

A guard is stronger than an individual player. It requires two players to work together to eliminate a guard, and being chased makes a player desperate for the other’s help. This makes the gameplay in singleplayer mode so hard to be right. In singleplayer, once the player is being chased, there’s no teammate to help.



The guards have the most complex AI to support the co-op experience. It is implemented by behavior trees. Guards’ AI states can be Idle, Suspect, Chase, Attack and Search and the transition states of them.

  1. In Idle state the guard is overwatching or patrolling.
  2. When a guard hears a small noise, he will turns to it.
  3. When a guard sees a player or a decoy, he will be suspecting.
  4. When a guard is suspecting for a while or receives an alarm event, he will turn on his radio, and start chasing at the players.
  5. When a guard meets a player while chasing, he will attack.
  6. When a guard can’t find any players in Chase state, he will start searching. In this state the guard will auto deduce where the player could be and search the floor.

To encourage the players to make an assault rather than lure everyone to a position with gun sounds. A special design is that when a guard is turning on his radio, he can’t attack at the same time. It takes quite some time. If the guard is lured by guns, when he meets the guard he will attack right away (because his radio was turned on when he started moving). This has a higher risk.


  1. 空闲状态下守卫会处于站岗或巡逻状态。
  2. 当守卫听到小的噪声时,会转头看去。
  3. 当守卫看到玩家或诱饵时,会进入怀疑状态。给玩家提供了一定的容错率。
  4. 当守卫怀疑超过一定时间时或听到警报事件,会打开无线电,并进入追逐状态。
  5. 当守卫在追逐状态下遇到玩家时,会进入攻击状态。
  6. 当守卫追逐玩家或一个警报事件时,当到达可疑位置找不到玩家时,会进入搜索状态。搜索状态下守卫会根据玩家的速度智能推断出玩家可能处于的位置并进行扫描。


Guard AI

Guard AI Idle

Guard AI Suspect

Guard AI Attracted

Weapons 武器

Guards have different types of weapons: - Assault Rifle: auto, low damage per shot - Laser Rifle: manual, high damage per shot - Shield and hand gun: low damage per shot, low fire rate, invincible from front. When the player is facing the guard, he will defend with the shield and shield bash the player; when the player is faced away, he will shoot the player.


Armors 护甲

Counters 克制关系

Signal Decay provides many types of weapons and gadgets to fight against enemies with different weapons and armors. The counters are mostly indirect.


Here are some examples: - Melee weapons are not useful against sentry guns with gun shields. - Taser can tase human enemies, but mechanical enemies are immune to it. - Energy Converter and Stabilizer are effective to low damage weapons, and are not that useful to manual and high damage weapons. - Active Barrier is effective to manual weapons on the contrary. - Stabilizer makes a good pair with Shotgun or Sniper Rifle. - Guards with shields and some robots scanning nearby places are counters to Shotgun and Plasma Dagger and are countered by Rifle and area of effect weapon like Heat Rifle.

以下是一些例子: - 近战武器很难对付墙壁上前面带盾的哨戒枪 - 泰瑟棒能定住人类敌人,但对机器敌人毫无办法 - 能量转化稳定器对连发低伤害武器效果显著,而对单发高伤害武器效果甚微。 - 主动屏障与之相反,对单发高伤害武器效果更大,而对连发低伤害武器没有什么效果。 - 稳定器霰弹枪狙击枪是不错的组合 - 使用盾牌的守卫以及会扫描和攻击附近威胁的机器人克制霰弹枪和离子刃等近程武器,会被远程武器如来福枪和范围伤害武器如热能步枪克制

See wiki for more details