The non-profit French organization MO5.com aims at preserving computer heritage. Though its primary area of expertise is hardwarepreservation, software preservation is also part of its purpose. Therefore, we have started working on software preservation. This leads to create some specific methodology and tools. Among software programs, video games and demos have a specific status. Indeed, unlike other software, they have no utilitarian purpose. Moreover, they imply the use of several art forms, being, at least, visual arts and music. Video games are highly interactive and dependent on the input and output systems, while one of the purpose of demos is to show off the highest possibilities of some specific hardware, as well as the skills of its makers.
To preserve such software, we are experimenting three different methods, we consider being complementary. The first one is to preserve numerical copies of the software as well as the hardware the software creators targeted to run on. The second method is to create the most precise emulator for this hardware. Such emulators being either software emulators (i.e., a piece of program that reproduces as accurately as possible the way the original platform behaves), or hardware (i.e, using programmable logic devices to reproduce how the original platform worked). Then, the piece of software can be run on these emulators. The third one being rewriting the software. That is, using as much as possible the original assets, making a software that behave just like the original one, but running on any modern computer, present or future. The point is that the new software must behave the most closely to the original. Each of these methods have their own successes and their own limitations. In this presentation, we will give an overview of each of these approaches.