In our database we hawe 2 file formats of .is1 file extension. If you have a problem with using .is1 file extension – we can help You. Below is a list of programs that support the file type of M3 Sakura Real-Time Save 1 File for all operating systems. If at any time in the future you will have a problem with any file extension, please visit our File Extensions Database. From today, the question - How to open file .is1 - There won't be a problem.