Top reasons to develop your own game engine in 2021

Unreal Engine 5 is soon to be released with new groundbreaking features, Unity dark mode is finally free and Godot 4 plans to take over the indie gamedev community. Why as an indie dev, would you skip all of those (plus many other production-ready game engines) and build your own custom game engine in 2021?

Next, we go through some of the decision reasons of choosing between Unity / Unreal / Godot vs Custom Game Engine. Lastly, we go over the reasons why we choose to build our own custom game engine for Threedly FPS.

When it is better to use Unity / Unreal / Godot?

The game will be a cross-platform game

Cross-platform is hard to get right even for seasoned developers as there are many moving blocks and undefined behavior. Most popular game engines are already tested and have built-in workaround for many issues.

You need proper content pipeline

If your game depends on or uses many imported 3D models and materials it is crucial to have working content pipeline. Content pipeline transform the imported 3D models and textures to game engine specific data format. If you want to import wide amount of different 3D model formats and have working texture compression, you might want to use off-the-shelf game engine.

You need to have realistic or next-gen graphics.

As an indie, it would be hard to stay at the same levels or even bring a new game engine to the levels of current off-the-shelf game engines.

Game has to be build in the shortest time possible.

It is hard to beat time-to-market with a custom engine. This doesn’t need any explanations.

You need to find people with existing skills to use the engine.

When you bring new people to the team in the later stages of the game’s development, you will be better of when they would have experience from the game engine you are using.

Game is a mobile game that ships for Android.

It’s pain in the ass to develop OpenGL ES for Android. Be prepared for graphics issues. There are so many different phones and OpenGL drivers with undefined or wrong behavior. I would chose proven game engine for mobile games (Unity / Defold).

You don’t have any specific and good reasoning for building a custom engine.

Lastly, if you don’t find any good reasons business or game design wise to develop a game engine.

When it is viable to build a custom game engine?

You care about fine-tuning underlying technical side

You need to tinker the fine details to have the minimal possible game distribution size and achieve the best performance. You need to customize or optimize the whole stack from raw input to rendering. You want to control the technology stack and optimize all aspects.

Your needs are well known before building the game

You can estimate the features needed for the game engine to build the game. This way you can have rough estimate, how long it will take to build the engine. And how big of a job it is to build the game engine.

Your content pipeline is simple and limited

For example, if your game design allows you to stick with one 3D model format and exclude textures with alpha.

The game doesn’t require next-gen graphics

This is self-explanatory. Sometimes less is more.

You think the game development will take more than two years or you want to provide updates for the game many years after the game release

After starting to build with Unreal / Unity / Godot, those will receive updates and the upgrade process for your game can bring game breaking changes that would need reworking levels and/or game mechanics. I have seen this happen for AAA game.

Why we have chosen to build custom game engine for Threedly FPS?

Threedly has to achieve lowest possible network and input lag

We need to have full control over the rendering loop, present swapchain and also input polling to fine tune the input and network latency.

Threedly has to be ultra-light and ultra-fast

We want Threedly to be small in distribution size, have ultra-fast start-up time and minimal loading times. Also the game performance should be excellent on low-end machines. We want the game to be non-intrusive, lightweight and accessible by people with low-end machines.

Threedly has simple visuals

This is both a game design choice and it also enables us realistically to develop custom game engine. We believe that visuals are very important but highly-realistic or candy graphics distract the core gameplay. Simple visuals also means simple content pipeline and simple rendering engine for the game engine.

We want to provide the map editor for the community

Yes, you can also build map editor with Unreal / Unity / Godot. But this comes as a bonus while building the map editor for the engine. It brings a bit more extra work to polish the editor for external users but we think it is worth it.

We are in it for the long term!

It is much easier to support future Windows versions and fix upcoming issues related to new hardware when you have control over the whole stack. If we would have chosen Unity or Unreal we would be stuck with the version we started to design with. If they would, for example, change the ray casting engine, physics engine, AI navigation engine or any core part of the engine in future versions, it could potentially change the gameplay drastically and to unwanted directions!

Threedly is PC-only game

It easy to focus developing the game engine to support only single platform. By focusing on single platform, we miss the headache of developing cross-platform abstractions and separate implementations.

Join Threedly FPS alpha

Threedly tactical team-based multiplayer FPS is still work-in-progress. You can join to alpha testing forces!