Updating Gun Rocket Through 10 Years of Unity Engine

The process of reviving Gun Rocket through over 10 years of Unity Editor changes.

The original project was built with the 2015-era Unity 4.6/5.5 lineup, and even the Steam build no longer ran. So the author first opened it in the editor to check its current state, then decided to do a step-by-step upgrade by major version rather than jumping straight to the latest.

• 5.6.7f1 → 2017.4.40f1: passed with almost no issues.
• During this process, the Package Manager appeared for the first time, and an empty manifest.json was added to the project.
• 2017.4 → 2019.3: the biggest hurdle.
  • Removal of JavaScript support meant 3 scripts had to be rewritten in C#.
  • UNet was no longer usable, so the game's LAN multiplayer was boldly removed.
  • AssetDatabase v2, Nested Prefabs, and the Prefab Editing Overhaul significantly changed the asset and prefab structure, but the conversion itself went through without trouble.
  • Old references broke, requiring several hours of work opening the 2017 and 2019 editors side by side and directly comparing prefabs.

After that, 2019.3 → 2019.4 had no major breaking changes, but the dark theme, UI overhaul, and automatic updates to deprecated APIs stood out. The author also has a small personal moment here, discovering their own name on Unity's internal roster.

The 2020–2022 stretch went more smoothly than expected, mostly leaving just line ending warnings. However, 2023.1 produced package cache errors, so the author ended up skipping it and moving straight to Unity 6000.3.12f1.

In Unity 6, DX12 became the default, OpenGL ES 2.0 was deprecated, and several API renames were handled automatically. The com.unity.ide.vscode package was also removed. In the end, the game ran correctly, and most of the remaining bug list was cleared out. Notably, a bug where the ship would explode if you stood still was also fixed.

Finally, the author reflects on how Unity 5.5 was small and scrappy but full of possibility, much like Godot is today, and compares how, as an engine grows, its features and install size tend to grow together.