Shiori's CatSystem2 engine (NEKOPARA Vol. 3): KIF archives, HG-3 images, kcScript and the FES screen scripts, in Swift, and the E-mote character renderer (PSB models on Metal) that KiriKit uses too. Part of Shiori.
It plays games you own; no game content is included.
Sources/CatSystemKit: the formats, the interpreter, the stage and the E-mote renderer.cs2-cli: lists archives, dumps scripts and exports images on the Mac.
swift build
swift testCatSystemKit's own code is under the Mozilla Public License 2.0. KIFArchive.swift and HGImage.swift follow GARbro's format code (MIT, morkt), credited in their headers.