Making A Game With Unreal Engine 5 In Four Weeks

Introduction

Hi, my name is Gabriel, and I'm a Senior Game Programmer who moved into indie game development in 2025. Before that, I served as the Head of Engineering at Proxima, where I released Suck Up!, a comedy game where you play as a vampire trying to convince people to invite you into their homes, which went viral in 2024.

Last month, I challenged myself to build a complete game in just four weeks as part of the Unreal Fellowship. The result was Jetpack Bubblegum: an explosive anime-style rail shooter where you level half a city while trying to save your cat. The demo will be playable at Unreal Fest Orlando from June 2 to 5.

Taking a game from a rough concept to a playable demo in four weeks meant taking advantage of every tool at my disposal. In this breakdown, I'll walk you through my journey, the techniques I used, and some of the lessons I learned along the way.

Is it even possible to make a game in four weeks?

When you only have four weeks, scope is everything. A senior developer taught me something in my very first year in the industry that I never forgot: "Whenever you're estimating a large project, just take whatever you came up with and multiply it by 2. Sometimes I even multiply it by 3."

It's so simple that I didn't want to believe it when I heard it, but it works every time. The reason I think it works is because it accounts for all the unknowns that always come up during development, and we are very bad at predicting beforehand.

With that in mind, I decided I was going to scope out the project to something I thought I could finish in two weeks, leaving the last two weeks as a buffer. Those were some of my key pillars to keep the project manageable:

• Focus on creating five minutes of a polished experience — just one level.
• Build around a simple hook that is easy to understand: you're an anime character trying to save your cat, but accidentally destroy half the city in the process.
• Use premade assets as much as possible to save time.

The challenge with working with pre-made assets, though, is making them all look cohesive. I relied heavily on Blender and Unreal Engine's tools for rigging and animation retargeting, and used custom shaders (UE5 materials) to create a cohesive look.

Even with this reduced scope, I couldn't fit in everything I had originally planned within the four-week deadline. But overall, I'm very happy with the end result.

Gameplay Prototyping and Juiciness

Since Jetpack Bubblegum was going to be playable on arcade machines at Unreal Fest, I knew the controls had to feel immediately intuitive and satisfying. So, my first task was to prototype the controls until I found something that clicked.

The main challenge was figuring out how to let the player move and aim at the same time. I ended up with a system where the player directly controls the crosshair, and the character dynamically follows its position.

Initially, I tried using Unreal's built-in CharacterMovementComponent. Although this component should work well for most games, because of the specific movement requirements of my game, I ended up writing a custom movement system from scratch in C++. This gave me full control over how the character tracked the crosshair and moved through the environment, which was essential for the fast, fluid gameplay I wanted.

For juiciness, I focused heavily on hit feedback, sound effects, and visual effects. I always love how much these small details add to the game's feel. It's really night and day when you compare them side by side:

And of course, we have to see some explosions! I found this stylized explosion asset on Fab that really helped bring up the satisfying feeling when finishing an enemy.

Working with Animations

Last year, I made the decision to properly learn Blender, and it turned out to be one of the best decisions I could have made as an indie developer. It not only taught me a lot about art pipelines, but it also opened the door to an amazing ecosystem of plugins that can speed up development.

For this Jetpack Bubblegum, I used Blender mostly for rigging. I relied on Game Rig Tools, a pay-what-you-want addon that makes creating Unreal Engine 5-compatible rigs super easy. The author has a great walkthrough on how to create UE5 rigs in Blender with this tool.

What I didn't expect, though, was how much Unreal Engine itself would assist in the animation process. UE5's new animation editing features are incredibly powerful and allowed me to make a lot of custom adjustments directly inside the engine.

For example, some of the flying animations from this asset I was using didn't really fit the hovering visuals I had in mind for the main gameplay. Using a Level Sequence and an Animation Layer Override, I was able to tweak some of the bones while keeping the rest of the keyframes unaltered — all without leaving Unreal.

Using Custom Materials to Make Assets Work Together

A lot of people think that a game's visuals are decided when the artist is making the assets. But in reality, most of the final look happens inside the engine, through shaders, post-processing, and lighting. Because of that, you can go a long way using assets from different artists if you know how to unify them in the engine.

Since Jetpack Bubblegum is an upbeat, anime-inspired game, I decided to go with a cel-shaded material combined with an outline effect done via post-processing.

The character shader is a simplified version of Ben Ayers' Genshin Impact shader — I didn't have time to implement all the amazing effects he added to his, but the basic structure is the same.

As for the outline material, I learned most of the implementation from one of Epic's Live Training. The gist of it is comparing the scene depth value of the current pixel with the surrounding pixels. If the difference is above a certain threshold, we get an outline.

Once I started bringing in drones and enemies from different asset packs, the key was making sure everything used the same shading model. The challenge, of course, is that most marketplace assets are built completely differently. For example, one artist used a full PBR workflow with albedo, normal, AO, metallic, and roughness textures, while another used packed texture channels for color tints and masks.

In the end, I had to write a custom shader for each major model. It's not the most efficient setup, but it was good enough for the prototype. When it's time to polish the full game, I'll need to consolidate everything into a unified material system.

Environment and UE5 Chaos System

One of the big hooks of Jetpack Bubblegum was real-time environment destruction — something Unreal Engine 5's Chaos system is especially good at.

There's a lot that goes into setting up destructible environments in UE5, but at a high level, the process is pretty straightforward: you create a Geometry Collection from your mesh, then fracture it a few times to define how it will break apart.

In practice, though, there are a few important lessons I learned:

1. Fracturing a mesh too much can have a big impact on performance, especially once physics simulation kicks in.
2. You want to make sure there's enough internal geometry inside your structures. Without it, buildings will crumble too easily after the first hit

In the end, I'm not completely happy with how destruction feels in-game. I think I should have spent more time tweaking the geometry collection settings and adding internal geometry to the buildings. But with the four-week deadline, I had to prioritize converting all the buildings from the Tokyo City asset pack into Geometry Collections so they could make it into the game.

Closing Thoughts

In the end, making a game in four weeks isn't that different from making a commercial game. You need to figure out what's really important, focus all your energy there, and take every shortcut you can — because the ship date always comes! 

The surprising twist for Jetpack Bubblegum, though, was how much the project grew on me over those four weeks. And after seeing the warm reception from the gaming community as I shared my progress, I decided to keep developing Jetpack Bubblegum into a full commercial release.

If you also want to know what happens with Mr. Muffin and follow my journey shipping this game as a solo indie dev, you can find me on X or join our mailing list to get notified when the public demo is out!

Gabriel Dechichi, Senior Game Programmer / Indie Developer