ModulysCS is built around ModulysVst which is a giant step-sequencer/phrase generator in Vst-plugin format.
ModulysCS is a portable app for Windows (15MB zip-file) and includes a Csound CSD-editor.
Own presets and instruments can be created by the user.
It uses Csound 6.15.0 api for communication and sound generation.
It’s totally free without restrictions.
For more info see