The commercial vindication came swiftly. Slay the Spire 2 sold over 3 million copies in its first week, generating approximately $75 million in gross revenue before Steam's share. For an indie developer, these numbers represent validation at scale. Yet the narrative beneath those figures carries a more instructive lesson about the consequences of corporate overreach and the calculus developers face when platforms change the terms of engagement.
Mega Crit's decision to build Slay the Spire 2 using Godot, a free and open-source game engine, was not made from the outset. The developer had already spent over two years building the game in Unity before committing to switch engines. That choice carried real costs: porting a game of this complexity is neither quick nor cheap. Yet the developer made the leap anyway, and one direct factor forced the hand.
In September 2023, Unity announced a policy that would charge game developers a fee each time their game was installed, provided certain revenue and install thresholds were met. Under the original proposal, developers would have been charged 20 cents per install for games with more than 200,000 installs and over $200,000 in annual revenue. The policy was framed as an investment in the engine itself, but developers across the industry saw it differently. Many developers viewed it as a betrayal of Unity's longstanding mission to democratise game development.
Mega Crit responded with an unusually direct public letter directed at Unity, stating "We have never made a public statement before. This is how badly you fucked up." The developer announced it would switch engines if Unity did not completely reverse the policy. This was not a vague threat. It was a pledge to surrender two years of work rather than remain on a platform the studio no longer trusted.
The broader developer community joined the outcry. Among Us developers Innersloth said pulling the game from the platform was an option, with a programmer stating "We're lucky to have the resources that we could swap engines and I see no reason to pay Unity for nothing while we do it". The backlash proved consequential: While Unity eventually backtracked on the per-install fee, the controversy led to the resignation of CEO John Riccitiello.
Yet Mega Crit did not reverse course. Even after Unity backed down, the developer stuck with the engine switch, with Godot confirmed as its chosen platform. This follows a wider pattern. Other developers cited trust issues when deciding to switch engines, with some jumping to alternatives like Godot or Unreal to avoid future surprises.
The significance of Slay the Spire 2's success extends beyond commercial metrics. Whether Godot is adequate for professional game developers seeking a Unity alternative was debated when it entered the spotlight, but Slay the Spire 2 appears to demonstrate that for certain kinds of games, it can do the job. More broadly, the game illustrates how a dominant platform's misjudgement can catalyse migration toward alternatives, even when that migration demands substantial reworking of existing projects.
From an institutional standpoint, the episode underscores a principle that applies across technology platforms: developer ecosystems rest on trust as much as technical capability. Once that trust fractures, the cost of rebuilding it exceeds the cost of the original error. Mega Crit's choice to leave, despite the sunk investment, signals that the calculus is shifting. Godot remains under active development and is now demonstrably capable of supporting commercially ambitious titles. Mega Crit has made sizeable donations to Godot, and the exposure is important in conveying that large-scale commercial success is achievable with the open-source engine.
Whether this moment represents a genuine inflection point for game engine market share, or merely a successful outlier, will become clear over the next few years. What is certain is that Unity's 2023 gamble—perceived by developers as an attempt to retroactively change the licensing terms of their own work—has cost the company a high-profile title and damaged its standing within the community it depends upon. For Mega Crit, the decision to switch proved not merely defensible, but commercially vindicated. In technology, such outcomes reshape incentives for everyone else watching.