Hello!
Big fan of the project, I have had lots of fun playing it and it is pretty amazing what you have managed to achieve here, really revitalized it for me. I have been a gaming artist for the past 15+ years because of games such as this on the Amiga inspiring me throughout my whole childhood.
There is one really small detail that always bugged me from the original game which it took me less than 10 min to fix, and I wonder if it is something you'd be interested in looking to fix/update; In the original Turrican, the running loop animation had a visual error where the arms sway parallel to the legs, which is of course incorrect. I have simply sifted the upper body loop cycle halfway with the legs and the run feels a lot more natural.
Anyways, only a suggestion, and thanks again for this little gem!