I have no idea which engine, but the minified source has this in it

https://www.balanc3dgame.com/assets/index-53e87cdf.js

* react-dom.production.min.js * react-jsx-runtime.production.min.js * react-reconciler-constants.production.min.js * react-reconciler.production.min.js * react.production.min.js * scheduler.production.min.js * use-sync-external-store-shim.production.min.js * use-sync-external-store-shim/with-selector.production.min.js

It turns out it's just ThreeJS (react-three): https://github.com/nargaw/Balanc3d_game