Alex Ning 
Slay the Spire is a popular deck-building roguelike video game made by Mega Crit Games with Unity Engine. However, the developers switched to a completely different engine for Slay the Spire 2, the sequal of the game that has been recently published. This seemingly simple change of tool revealed a hidden conflict between game developers and software companies.
Paid VS Free: Differences
Unity Engine is a game engine developed by Unity Technologies. The engine included many assets and tools that helped developers to create video games more easily. This engine is free to download, and charges money from developers only if the revenue generated by their Unity game surpasses a certain threshold. This system brings profit to Unity Technologies and at the same time allowed indie developers to start using the engine without worrying about losing money.
On the other hand, Godot Engine is a open-source free engine. This means that anyone is free to use, modify, make games with, and make money with the engine. However, being free means that the developers of the engine are mostly volunteers, and therefore the engine is less powerful than the paid Unity engine.
The Change
In the year 2023, Unity Technologies announced a sudden change in their charging policy: instead of charging according to revenue of the game, developers have to pay money according to how many times their games were downloaded. This raised a lot of controversies: If a game is bought once and downloaded multiple times, the developer have to pay Unity more money, even if they only earned little. Furthermore, the way Unity calculates download count is not transparent, which means Unity suddenly gets to decide how much money developers should pay to them.
As the controversy intensifies, Unity backed down, but this change in charging policy had already created distrust, and many game developers switched to Godot Engine, where everything is open, transparent, and free. Mega Crit, the developers of Slay the Spire, is one of those developers. After the release of Slay the Spire 2, Mega Crit had created the largest Godot game ever, proving that open source engines created by communities can be useful tools that are not inferior to paid engines made by companies.
