Wired has translated and posted an academic essay by Italian film scholar Federico Giordano on the problems with archiving video games:

Videogames come to us as a form of media which have, on the one hand, some affinities with other previous forms such as cinema, television, technological parks, board games or role-playing games, and even panoramas and dioramas. It is this aspect in itself that makes videogames a medium that can be “archived.”

On the other hand, videogames seem to be a decisive break from these forms. They develop themselves as a specific system of relationships between the text and users.

He identifies three guidelines (borrowed from the KEEP project) for archiving – a) storage, b) transfer and c) emulation.
Here’s a section on emulation:

The “emulation” of Bionic Commando, as with other such games, is not the same as its “storage.” Emulation fails to preserve in detail the experience of the original game, and it certainly cannot store the physical support which was part of the game experience. Generally, emulated games alter the game rhythm, the rendering of the graphics, and the sound, changing the spatial and temporal performance of the original games.

Amiga can be reproduced only partially by WinUAE or other emulators, due to the internal limits of the software. The response time of old joysticks and keyboards, which are different from Gamepads and today’s controllers, make it intrinsically impossible to reproduce the game experience.

via The Escapist