@SolarLune said:
Eh? Why not just download an older version of Game Maker to open the project files?
That's a temporary solution; eventually core OS functionality improves to a point where old software, if not maintained, fails to run correctly; compounded, as the software ages, new editions of it get bug fixes and new features, you're constantly being left in the dust with no hope of help. Maintainers of add-ons to that software are pressured to update their software as well, to keep up with the newer editions, so you're left in the dust twice if you choose to use the older software, unless the maintainers choose to support multiple editions which they're unlikely to for long, opting to favor the newer, more feature-rich environment not just for the fact that more users are likely to be interested in that and interested in using the add-on for that, but it's also just nicer to have those extra features in general.
As time goes on, the feature updates become impossible to ignore. There was a time where iOS and Android did not exist, and if you were to use software from that time period, you wouldn't be able to publish to those platforms; even afterwards, there's times where software just doesn't have this ability at one point in time, but later it does. A new console comes into existence, what will you do with your old version of X-software to be able to target that platform? Some new technology comes into existence, like Vulkan, and it turns out to be a hit, but you can't take advantage of it because your software is out of date and has no concept of it whatsoever. A new standard comes into existence, like HTML6, and your outdated software doesn't understand how to work with it and it isn't compatible with your HTML5 code; alternatively, newer versions of iOS, Android, or just about anything else are incompatible with how your engine is handling them; you're stuck, you have to upgrade to publish, you can't expect your users to downgrade to play your game, there are just way too many games in existence for them to bother; they will (reasonably) consider you the problem, not them. Even if your game is PHENOMENAL, it's a huge barrier of entry for the vast majority of gamers, even the more technical ones (not to mention the security problems that might introduce.)
That's just platform-related. What happens when a new edition of that software introduces a killer feature that you've been dying for and which will make your design process infinitely easier? You see my point.
You're better off just not dealing with that problem. YoYo Games developed a trap, your best hope is to avoid it.