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People have been altering plays for ages without much issue (just look at the mod community), emulating and porting plays to different stages, and even reverse engineering their own copies of the script.

The only real catch has been online stuff and even that is sometimes worked around or recreated. It's not an impossible task to solve the problem of making games playable into the future, but it'll probably require legislation to force game companies to preserve their game and server code to allow for it.