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Weapon Merge (Unity C#)


On February 8th, 2021, my master program classmate, Eunice Lim, invited me to participate in Mini Jam 73, which is a 72-hour-long, game development jam. However, the game jam was going to close the submission gate in 3 hours when we decided to join, so we actually built the first version of this mobile/web physical game in a mini jam of a mini jam and we ranked #104 out of 179 entries.

The theme was "Power" and the limitation was "only display 5 colors (RBG/Hex values) on screen at once". Therefore, after half an hour of brainstorming, we chose "weapon power" to match them and a black-n-white hand-drawing style to reflect the desolate feelings of battlefields and trenches.

Three-Hour Game Jam Version

Circles vs. Irregular Shapes

I'm always up to date with trends in the global video game markets and put many thoughts on how particular ideas can be taken to another level. The initial design of the game was inspired by a fruit merge game that was very popular on Chinese social media. We wanted to make some big changes to its design and the first thing that came to our mind was keeping the irregular shapes of different types of weapons. Interesting movement can be caused by spawning, merging, and bouncing. However, the sharp corners of the weapons also caused many obstructions during the playtests, so eventually we decided to put all the weapons inside round bubbles to have a smoother gameplay.

Code Simplicity

The codes for the core gameplay were written within the last two hours of the game jam, even the latest version is still an improvement of those short scripts. Those codes not only created systematic deep strategies with physics-based mechanics but also guaranteed the delivery of the 3-hour scope.

Balancing Physics

We spent a lot of time during and after the game jam to tune the physics-related data, like the sizes, mass, and frictions. Too much size increasing can make the high-level weapons occupy a huge part of the screen, but too little size changing is not obvious enough for the players to figure out which types of weapons have higher levels than the others. We don't want the weapons or bubbles to fly around the screen (especially after we added the deadline since the bouncing bubbles can easily touch it and end the game); while the weapons can't have enough movement if they are too heavy or their frictions are too big, which makes it impossible to merge those covered by others.

Win/Lose Conditions

In the game jam version, we tested out changing the win/lose conditions from pursuing higher scores to merging to the nuclear bomb (you can see the BOOM screen above). This design would lead the players to pay more attention to upgrading the same weapons, which requires different strategies from the original idea. But it would lack replayability at the same time.

Mobile & WebGL Versions

Latest Gameplay Video:

UI Improvement

We kept working on this game for months after the game jam and successfully released it on, Google Play, and App Store. From the feedback and reviews on those platforms, UI is what we can and need to improve the most. The UI elements on the top changed from dark grey to white, and I fixed the anchoring issues on different resolutions so the texts won't block the weapon spawner (the claw drove by the kitty). I also moved the combo text from the top center of the screen (some people didn't even notice it)to dynamics positions next to the merging weapons. Eunice designed a color bar under the spawner to indicate where and which color the next weapon is going to spawn (this is very helpful in the double color mode).

Mechanics & Systems

Spawn, Merge, Upgrade

A mechanical claw operated by a kitty soldier moves horizontally above a battlefield trench always carries a weapon bubble. The players can decide when and where to release the bubble by tapping/clicking on the screen. The colors and types of the new weapons are completely random, but their levels won't be higher than the highest level in the current trench. When two same-level weapons collide with each other either in falling or rolling, they will immediately disappear and a next-level weapon will appear at the center point of them.

Single/Double-Color Modes

Double-color mode definitely requires more strategic thinking in the overall arrangement than single-color mode. The players feel a sharp increase in the gameplay difficulty. Therefore, we try our best to remove any interference elements, like sometimes mistake one color for another. We are also planning to separate the leaderboard for both modes and give the double-color mode better rewards.

Combo Merge

In the middle of the game, a new spawned weapon bubble can cause several other bubbles to make interesting movements. To encourage the players to put more effort into the low-level weapons in the trench, I built the combo system and its dynamic UI.

Cross-Platform Leaderboard (Mobile)

During our playtests, almost every player wants to how many points have other players made. Therefore, I coded a Share button that will take a screenshot of the current game screen and allow the users to share via social media. We are also building a leaderboard system that links both Android and iOS platforms.


We switched the game goal from upgrading to the highest-level weapons to avoiding touching the deadline which locates between the spawn claw and the trench. We felt that it is not fair if the weapon bubbles bounce up and collide the deadline can directly end the game, so we added a timer and flashing effect on the deadline to warn the players that they have to figure out how to reduce the height of the stack of bubbles in a few seconds.

Earthquake Shake

Earthquake Shake is our first attempt to build a skills/tools system that will add more gameplay mechanics, strategies, and monetization potentials. This skill started with a solid strength upward force, but it either shoots all the bubbles outside the trench when there're too few bubbles or can't move a single weapon when there're too many. So I wrote a formula that makes the force increases with the number of bubbles in the trench. Besides, the skill had an instant cooldown, which became a cheating method since our game is untimed. Currently, I gave it a five-second cooldown, which will make many players lose their patience to use this skill too many times. In the future, we will try to limit the times of using skills by adding a skill spawning system or linking it with in-game purchases.

More Ideas

PVP Mode

We still collect suggestions and do brainstorms these days, and PVP mode is one of the ideas that we really want to implement. In fact, the double-color mode was inspired by the idea of spawning different color bubbles to block each other's merging. Another way of competing with other players is using disrupting skills or tools.

Monetization & In-game Currency

Like other casual F2P games, Weapon Merge can be benefited from in-game purchases. The players can buy new skins, skills, tools, decorations to enjoy advanced gameplay and reach higher scores much easier. We also consider having in-game currencies which can be purchased or obtained during the game.

Skins Shop

Our current art theme is a cat soldier on the WWII battlefield. Apparently, the cat-lovers should have options of different breeds, and the military or history enthusiasts can choose various war themes. The new sets of weapons, like Ancient Japanese weapons, Medival weapons, or Sci-fi weapons, will also appear with this skin shop.

Skills/Tools System

Like Earthquake Shake, we want to design more one-time-use or limited-amount special skills to enhance the gameplay experience. We have the ideas like:

  • Tapping bubbles to destroy

  • Fliping bubble colors

  • Changing weapon types

  • Longer deadline timer


Every time the players upgrade to a new-level weapon, the collection gallery will unlock the artwork of it. We can also add some special versions of each item which will randomly spawn in different modes. Therefore, the players will have more initiative to play over and over again.


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