libGDX
A mature, cross-platform Java game-development framework built on OpenGL (ES). Apache-2.0, framework-based (no bespoke editor — you code against an API, Gradle-based setup), supporting both 2D and 3D. Targets desktop (Windows/Linux/macOS), Android, iOS, and the web through distinct backend implementations. ~25.2k★, a large third-party-library ecosystem.
Where it sits in the field
- Framework cohort. Joins the framework-based engines Flame (Dart), Phaser (JS), LÖVE (Lua), and Bevy (Rust) — the “code-against-an-API, no editor, minimal footprint” bet. Its distinguishing coordinates: Java (a new language on the spoke’s language × host-runtime axis) and, like bevy, 2D and 3D rather than 2D-only.
- Licensing: Apache-2.0, on the permissive open-source end with godot-engine/o3de/ torque2d.
- Commercial credibility. A mature framework with shipped commercial titles — the repo showcases Pathway (Robotality). It demonstrates the code-first framework path can ship real games, not just prototypes.
- Possible tie to the migration arc (flagged, unverified). The original Slay the Spire is widely reported to have been built on libGDX (Java) — which, if accurate, would complicate the mega-crit page’s framing of Slay the Spire 2 as a “Unity → Godot” migration (it may have been libGDX → Godot, or StS used more than one stack). The libGDX repo source here does not confirm the StS connection (it lists Pathway), so this is recorded as an open question to check against a first-party Mega Crit source, per record-don’t-overwrite — not asserted.
Related
flame-engine · phaser · love2d · bevy · mega-crit · godot-engine · synthesis