GAME DESIGN DOCUMENT

DOWNLOAD AND PLAY

Grenade Quest is a stealth game based only on grenades. The protagonist is a goblin rogue and the story is set in a sci-fi universe.

The layout of the levels and the behavior of the enemies enable three different approaches: full combat, full stealth and mixed.

Team size: 1
Genre: Stealth
Duration: May 2021
Engine: Unreal Engine 4

The prototype is set in a lab surveilled by robots. You must go to the lower floor, pick the teleport grenade and then leave the building (you can use the teleport grenade on your way out).

Design goals

• Play as D’Jagger Rahoud (the protagonist of my novel HoJ – 1 – La frontiera perduta)
  • He fights using only grenades
  • He can craft grenades and other technological things
  • He is agile but weak
  • He is a funny rogue
• Levels must allow multiple approaches:
  • full combat: destroy all robots, ignore the optional keys and destroy the obstacles (you must be careful anyway because the robots can kill you with a single shot)
  • full stealth: use only the bait grenade (and later the teleport grenade), find grates and optional keys to unlock other passages
  • mixed
• Outsmart your enemies

Core pillars

The grenade-based combat system and the design of the enemies encourage a stealth approach, but the gameplay involves combat, exploration, and crafting. Each pillar supports the other two.

The game encourages the player to move slowly and to evaluate the situation before acting (which is why looting and opening grates take a few seconds). Nonetheless, the game features frequent checkpoints, so the player can also experiment through trial and error.

Grenades

They are the only tool available to the player, but there are many of them for different uses.

The grenade-based combat system focuses on the following challenges:

1. Hit the enemy with a grenade
   1. The most basic objective is to hit an unaware enemy. The player must predict the movement of the enemy because grenades are slower than a common projectile.
2. Hit the enemy with a grenade without being detected
   1. The player must be careful because the noise of the grenade might alert nearby enemies.
3. Hit the enemy with the proper grenade
   1. Some enemies are immune to some grenades, so the player must take this into account.
4. Hit multiple enemies with a single grenade
   1. This can be very rewarding for the player, but it might also be necessary for certain situations because the supplies are very limited.
5. Use the grenade to direct the enemies
   1. You must plan carefully where and when to throw the grenade in order to distract enemies or to direct them toward a certain area.
6. Use the grenade to break the obstacle
   1. Grenades can break certain obstacles, opening new paths.
7. Use the grenade to ignite the flammable barrel
   1. Some grenades can ignite flammable barrels, causing a big and very noisy explosion that can kill many enemies at the same time. It can be used in combination with directing the enemies toward the barrel.
8. Place a triggerable grenade in the path of the enemy
   1. Once you have understood the path of an enemy, you can place a triggerable grenade that will explode as soon as the enemy enters its area of effect.

The player can craft new grenades by collecting the proper materials. The player obtains 3 materials of a single type from each source (defeated robots, flammable barrels, and ammo boxes), the maximum amount of materials is 3 per type. The grenades are crafted on the fly when you throw them.

Name	Effect	AoE radius	Loudness	Noise type	Material
Wide impulse	Stun, break destructibles	400	Loud	Alert	Impulse emitter
Focused impulse	Kill, break destructibles	200	Loud	Alert	Impulse emitter
Electric	Stun, ignites flammable barrels	200	Quiet	Noise	Electro core
Burning	Kill after [5] seconds, ignites flammable barrels	300	Quiet	Alert	Flammable liquid
Bait	It just makes noise		Loud	Noise	Nothing (unlimited)
Teleport	Teleport to impact location		Quiet	Noise	Nothing (you can reuse it after a cooldown of [2] seconds)

You can choose between three triggers for the grenade:

• explode on touch
• explode after 2.5 seconds
• explode when an enemy enters its area of effect

The timer-based grenade may seem less effective, but some players underlined the fact that in most games the grenades do not explode on touch, so the timer-based grenade has a more natural behavior.

The sensor-triggered grenade offers a more strategic approach, moreover the enemies cannot find out the location of player when they hear the explosion of a sensor-triggered grenade. The player can also pickup the grenades she has placed if they haven’t been triggered, this will restore 1 of the corresponding material.

Robots

Each robot can have a patrol path or a position to guard.

Each robot has a weapon. There are two types of weapon:

• stun rifle: medium range, medium accuracy; can be looted to create electric grenades
• impulse shotgun: short range, high accuracy; can be looted to create impulse grenades

Each robot can be immune to one type of grenade:

• regular robot (white): vulnerable to all grenades
• isolator armor (yellow): immune to electric grenades
• fireproof armor (red): immune to burning grenades
• heavy armor (gray, bigger): it has a supplementary armor that must be broken with a focused impulse grenade
• drone: it is vulnerable to all grenades, stun grenades will destroy it as well

The player can see enemies through walls and ceilings. The color highlights the weapon and the type of body.

Due to the feedback received from the players, I emphasized the difference between stunned robots and destroyed robots. Moreover, a robot cannot wake up from the stun state if you are looting it.

Behavior

The behavior of the robots is defined as a behavior tree based on 4 levels of alert. A colored led on the face indicates the alert of the robot:

• none (white)
• low (blue)
• high (yellow)
• very high (red)

When a robot hears a noise, its alert is increased. The robot will emit a sound when its alert increases. There are two types of noise:

• generic noise (bait, electric and teleport grenades): raises the alert by 1
• alarming noise (explosion, impulse and burning grenades): raises the alert by 2

Seeing the player will raise the alert of the robot depending on the distance (if the player is far, the alert will raise slowly).

After checking the noise or loosing sight of the player, the alert is decreased slowly, so the player must plan more carefully her moves.

Levels

Levels must allow multiple approaches (from full combat to full stealth).

The levels implemented in the prototype have a high focus on stealth and careful movement, so they are relatively small and offer many options for taking cover.

Each level has some safe spots where the player can stop to analyze the surrounding and understand the path of the enemies.

Each level has a peculiar layout and each room is clearly differentiated from the others, so it’s easier for the player to navigate them.

The overall difficulty is the roughly same for the full-combat and full-stealth playstyles, but the moment-to-moment difficulty is not homogeneous. This is a desired effect, in fact, the player can choose the optimal playstyle according to the situation, or she can choose to complete the levels using only a specific approach for an extra challenge (it also increases the replayability).

The difficulty raises gradually and in a non-uniform way, so the game will alternate more tense and more relaxing situations. This will help the player to stay in the flow.

Level 1, Floor 0 of the lab

The level has two planes to add verticality. You can move from one plane to the other using three ramps (one in the first block on the bottom left and two in the main block).

The player will traverse this level twice: the first time from the starting position to the elevator in order to reach the lower floor (Level 2), and the second time from the elevator to the starting position in order to leave the building.

To unlock the elevator, the player must enter the control room over the elevator, which is locked as well. The player can find a key in a room on the bottom left or she can blow up the window with an impulse grenade.

The player starts in a safe position in a small room (bottom left in the image) where she can immediately loot a broken robot.

The player can face the single robot or can use the grate to reach the main room.

The image above shows the minimal paths required for the stealth-only (blue) and combat-only (red) paths, nonetheless the player must be careful to avoid the robots or to destroy them without being spotted.

Main changes with respect to the initial sketches:

• more enemies
• more obstacles that can be used to hide from the enemies
• light supports that can be used to move around, they are rechable from the upper area

In the stealth walkthrough I find the key for the control room before reaching the control room itself (the lock), which is not ideal.

In this level there are:

• 4 standard robots (only 2 will be present after stealing the teleport grenade)
• 1 fireproof-armor robot
• 1 isolator-armor robot
• 3 heavy-armor robots (only after stealing the teleport grenade, two of them will replace the standard robots)
• 2 drones (only after stealing the teleport grenade)
• 1 broken robot

The alternative robots are an interesting variation for combat-oriented players, but they can also be useful for stealth-oriented players because they have a different aesthetic, so the players can easily identify them and understand their patrol path.

Enemies progression (toward elevator)

Enemies progression (toward exit)

Screenshots of the level

Level 2, Floor -1 of the lab

The second level is bigger than the the floor 0 and it features two main rooms divided by an empty room that corresponds to a checkpoint. In the level there is also a vault that contains the teleport grenade and it must be opened using the corresponding key.

In the first main room, the player can search for a key in the rooms on the upper plane, or she can blow up the fragile wall on the bottom left of the room.

In the second main room the player must find the key to open the vault. In this case the player can destroy the robots or use a ventilation duct. The vault is guarded by a heavy-armor robot.

Once inside the vault, the door closes and the player must use the teleport grenade to reach a grate, which is the only way out.

To return to the elevator, the player can use another ventilation duct that can be reached only with the teleport grenade.

Main changes with respect to the initial sketches:

• added checkpoints
• more enemies
• more obstacles that can be used to hide from the enemies
• light supports that can be used to move around, they are rechable from the upper area
• an additional ventilation duct that can be used only on the way back to the elevator
• an additional optional item (a collectible)

In this level there are:

• 2 standard robots
• 2 fireproof-armor robots
• 3 isolator-armor robots
• 1 heavy-armor robot
• 1 drone

Enemies progression

Screenshots of the level

Quest

The prototype is part of a longer quest.

The quest starts when the protagonist, D’Jagger, finds out that some criminals who betrayed him want to steal something from a lab. He then decides to steal it first. This is the main goal of the quest and will guide the following actions of the protagonist (and of the player).

He enters the lab, which is surveilled by robots. He can destroy them or avoid them.

In the lower floor he finds out that the thing is a Portable Teleporting Device (the teleport grenade).

After taking the teleport grenade, an alarm is triggered and he must leave the deposit while the robots are in alert. New robots are deployed to replace the ones he has previously destroyed.

He leaves the lab with the teleport grenade, but now the building is surrounded by the criminals. He can defeat them or try to sneak away undetected.