1- CSswitch
2- Doukutsu-rsis a custom engine recreation.
works with any cave story data
https://github.com/doukutsu-rs/doukutsu-rs
3- Rain's DS port is based on CSE2 and open source. (binarys are ok to distribute)
https://github.com/tilderain/CaveStoryNDS
coop guide is in the link
but if you...