A TURN-BASED STRATEGY GAME
FEATURING UNIQUE AERIAL COMBAT TACTICS
Operation Cumulonimbus is a turn-based strategy game of aerial combat, set in an alternate World War I with advanced science.
Taking advantage of planes’ inability to hover in midair or make sharp turns, the game offers a fresh strategic experience unlike any other strategy game.
Generate clouds to obscure vision, drive enemies into thunderclouds to destroy them, and place obstacles directly in their path so inertia leads them to their own downfall.
With only a handful of allies, fend off endless waves of foes, and claim victory by controlling more territory than the enemy when the final turn ends.
Youngjun Lee: Game Designer & Programmer | Lexi He: 2D Artist | 3D assets sourced from Sketchfab.
- SINCE May 2025 -
This video will be explained in more detail later.
Basic Game Loop
Pre Game Setup
Before entering the battlefield, the player can visit the Defense Contractors to buy the actions and upgrades.
Then they set up each unit in Headquarters.
After assessing the battlefield situation, the player organizes their units into a 5×5 grid so it is ready to deploy.
Player Starts,
After assessing the battlefield situation, the player organizes their units into a 5×5 grid and deploys them at the desired positions on the map. The game begins with the player’s turn, allowing them to expand the frontlines and prepare for enemy attacks.
Unlike many other strategy games, this system emphasizes the freedom of unit placement, encouraging strategic choices from the very first turn. By starting with the player’s turn, it prevents the first turn from being wasted on meaningless movement and instead helps the player establish a clear and intentional frontline.
Enemy AI Ends.
The player’s goal is to secure a larger area than the enemy by the final turn. However, since each turn proceeds in the order of Player → Enemy AI, the area is only calculated after the enemy’s move. This means the player cannot let their guard down until the very end, addressing the common issue in many turn-based strategy games where tension drops once the endgame begins.
Key Features
Planes Cannot Stop Mid-Air
Planes require lift, so they cannot remain stationary in midair. Therefore, plane units must move forward a certain distance each turn. This is one of the key features that distinguishes this game from other turn-based titles, providing players with various tactical options.
For example, if the player places an obstacle directly in front of an enemy unit, since that enemy unit will inevitably crash into the obstacle on its next turn since it is forced to move forward. Likewise, when moving the player’s own units, they must consider the minimum distance that enemy units will move on their next turn, so their units do not end up colliding with enemies in the following turn.
Planes Cannot Freely Change Direction
Since planes are unable to freely change direction, they become extremely vulnerable when their rear is exposed. To reflect this, airplane units can only change direction after moving to the edge of their movement range, and they cannot go backward. The interplay between each unit’s field of view, action range, and movement range encourages strategic decision. Like playing chess, units protect one another while probing the enemy’s formation for weak points to exploit.
Mid-Air Collisions Are Critical
Due to the nature of aircraft, even a minor impact can be fatal. Therefore, in this game, a collision between aircraft results in the immediate destruction of both. Players can use this mechanic strategically.
For example, the player can use action to change enemy’s direction and make them collide with each other or intentionally sacrifice a weaker ally to destroy a stronger enemy for tactical advantage. At the same time, players must carefully plan their movements to avoid collisions between their own units.
Strategic Terrain Customization: Cloud Generation
Clouds in the level serve multiple roles: they act as cover that reduces incoming damage, provide stealth opportunities for ambushes, and as traps when enemies are pushed into thunderclouds, leading to their instant destruction.
Players can actively utilize the clouds present in the level or create and destroy clouds at desired locations to reshape the terrain to their advantage. However, since clouds can also be used by enemies, players must carefully consider their actions to ensure that the terrain they manipulate does not end up trapping themselves.
Occupy Larger Territory to Win
The goal of this game is to control a larger territory than the enemy once all turns have ended. The player’s territory is defined as the geometric plane formed by connecting the outer units. All remaining areas on the level are considered enemy territory. This unique winning condition that is rarely seen in other strategy games offers following advantages:
As the player approaches victory, the game’s difficulty naturally increases, maintaining a sense of tension. The wider the player expands their territory, the lower the density between their units becomes, meaning fewer opportunities for units to cover each other. As a result, the player must constantly decide whether to concentrate units for stronger firepower or to spread them out to secure more territory.
When selecting actions or upgrading units, players are encouraged to consider factors beyond firepower, such as move speed, defense, and adaptability. Even if lacking in offensive power, players can still try various strategies, such as using superior mobility to target less-defended enemy zones, modifying terrain, or enduring multiple attacks to hold strategic positions. This creates a wide range of viable strategies and playstyles.
UNIT TYPES
FIGHTER
Fighters stand on the frontline to disrupt enemy attacks and expand the frontline.
Unit Type: Plane
Cannot stop mid-air, cannot move backward.
Passive Skills
Evasive Maneuver: Have 50% base evasion rate.
Supporting Fire: Automatically attacks enemy units within range if they attack allies.
GUNSHIP
Gunships trade defense for powerful armaments, delivering devastating firepower and long-range support to allies.
Unit Type: Plane
Cannot stop mid-air, cannot move backward.
Front & Rear Machine Guns
Equipped with 180° rotating machine guns in the front and rear, the gunship can attack without blind spots.
It can hit enemies in front and behind simultaneously, and deliver double damage to enemies on its flanks with combined fire.
BALLOON
Balloons move freely and generate/remove clouds to turn the terrain to its advantage.
Unit Type: Balloon
Can move freely and hover mid-air.
Cloud Control
Create clouds in empty spaces, upgrade or downgrade existing clouds, or remove white clouds. Use this tactically to gain terrain advantage.
Fragile
Balloon is destroyed instantly when taking any damage.
AIRSHIP
The airship serves as a flying factory, manufacturing balloons to compensate for the numerical inferiority of allies.
Unit Type: Balloon
Can move freely and hover mid-air.
Special Hull
The airship’s HP is reduced by hit count rather than damage amount, and it cannot recover HP.
TERRAIN TYPES
EMPTY
The empty space that any unit can stay.
WHITE CLOUD
Units have a 50% Evasion Rate against attacks passing through white clouds.
Units inside white clouds gain a 50% Evasion Rate.
DARK CLOUD
Units have a 75% Evasion Rate against attacks passing through dark clouds.
Units inside dark clouds gain a 75% Evasion Rate and become Unspotted.
THUNDER CLOUD
Units have a 100% Evasion Rate against attacks passing through thunder clouds.
Any unit that is forced into a thunder cloud, such as by being pushed, is immediately destroyed.
EXAMPLE
An attack passing through dark clouds has its damage reduced by 75%, while an attack passing through white clouds has its damage reduced by 50%.
Strategy Examples
Using the path that the enemy is guaranteed to move along 1
Since the enemy is a plane, it will always move forward.
Use the airship to create a balloon right in front of the enemy, forcing it to collide.
Sacrificing one balloon to instantly destroy the enemy fighter is a highly efficient trade.
Using the path that the enemy is guaranteed to move along 2
Since the enemy is a plane, it will always move forward.
Position units in front of the enemy’s path, so fighters can counterattack even during the enemy’s turn, and the balloon can create clouds to further increase the ally units’ evasion rate.
Customize the terrain 1
The enemy is surrounded by clouds, which reduces the damage it takes when attacked.
Attacks that pass through dark clouds deal 75% reduced damage.
A balloon removed the white cloud in front of the enemy, then the gunship can deal 100% damage.
Customize the terrain 2
It’s difficult to kill enemies with full HP at once.
However, balloons can create clouds, and by stacking them repeatedly in the same spot, they can be upgraded into thunderclouds.
The fighter can then shove the enemy into the thundercloud to eliminate it.
The thunderclouds placed on the field also serve as cover, protecting against enemy attacks during their turn.
FINELY ADJUSTED
NUMERICAL VALUES
HP, damage calculation, and action point usage are designed to stay within single-digit values, helping players intuitively grasp the magnitude of numbers and perform calculations easily.
Additionally, the relationship between odd and even numbers is actively utilized so that players perceive numerical calculations as counting steps.
9
All plane-type units have a fixed HP of 9.
n/4
Evasion rate is divided into four levels:
0%, 50%, 75%, and 100%.
4
Attack actions always deal a fixed 4 damage.
Together, these three values create a simple and elegant calculation system.
| Evasion Rate 0% | Evasion Rate 50% | Evasion Rate 75% | Evasion Rate 100% | |
|---|---|---|---|---|
| Damage per hit | 4 | 2 | 1 | 0 |
| Hits to Destroy | 3 | 5 | 9 | - |
| Formula | 4+4+4 ≥ 9 | 2+2+2+2+2 ≥ 9 | 1*9 ≥ 9 | - |
When the evasion rate is 0%, a unit will endure with 1 HP remaining after two attacks, and when the evasion rate is 50%, it will endure with 1 HP remaining after four attacks. This design has two advantages.
Strategically:
Players can make bolder use of units that survive with 1 HP. If a situation arises where an attack must be taken, it is more advantageous for a unit with 1 HP to receive the hit than one with 4 or more HP.
In addition, by exploiting the feature that both units are instantly destroyed when they collide, players can strategically sacrifice a unit with 1 HP to take down a unit with 9 HP and gain the upper hand.
If an enemy unit survives with 1 HP, the player must decide whether to spend one more action to finish it off, or to attack another unit to gain a numerical advantage depending on the situation.
Emotionally:
This design brings complex emotions to the player. If it is an ally that survives with 1 HP, the player feels great relief. If it is an enemy that survives with 1 HP, the player feels even greater tension.
Similarly, the use of action points and attack actions also relies on numbers that do not divide evenly.
3
Each turn, players get a fixed 3 action points.
2
Actions giving bonus action points provide 2 bonus action points each time.
2
Attacking actions always consume 2 action points.
| Initial Action Points (3) | With Bonus Points (3+2) | With Bonus Points (3+2+2) | |
|---|---|---|---|
| Available Attacks | 1 | 2 | 3 |
| Formula | 2 ≤ 3 | 2+2 ≤ 3+2 | 2+2+2 ≤ 3+2+2 |
Players are encouraged to make strategic choices by combining attack actions (2 points) with other actions (1 point), ensuring no action points go to waste.
Development Process
Credits
3D Assets: https://skfb.ly/6WRVP | https://skfb.ly/pxwOs | https://skfb.ly/6YstM | https://skfb.ly/oBsRn
2D Illustrations: Lexi He
Click the image to view the process in Unreal Engine 5.