When I think about the level of late '80 - first '90 creativity I am always reminded of a true classic:
This is fucking cool, imo. Limiting oneself because it "breaks reality" is stupid as fuck.
It's not that that Hobbes is rolling his eyes over, but Calvin's tendency to randomly alter shit on the fly that left it a disjointed, chaotic mess. You try to make a game, or any activity to get people involved and interested in, making rapid right angle turns to what is established s is not the way to maintain their immersion. All games have rules, everything people do are games when they are distilled down enough and it's for that reason that we despise real chaos in life. It has no rules and changes too quickly to establish any. If you think you don't like rules, all you really dislike are overly restrictive ones that inhibit any changes to established patterns, not the essence of rules themselves.
This is encapsulated in any comic where Calvin tries to play with someone other than Hobbes, like Susie, where just as Susie is getting into what has been established as their game, Calvin changes the rules turning things upside down and eventually pissing her off enough she refuses to keep playing with him.
Even then Calvin is playing by rules, but ones that only allow him to play by himself either due to their chaotic nature or antisocial bent, which is why he has Hobbes around, despite Hobbes' more mature, jaded and orderly outlook.
The problem here isn't when stuff "breaks reality" but when massive, dramatic and unforeshadowed changes happen in a medium. With regard to Grimoire that would be it suddenly becoming overly serious about the lore or doing anything that would violate the rules Cleve established in the game that form its tone.
It is why drops in the quality of games are so apparent and hated. People expect the quality to be maintained and would be fine with a game being of lower quality all the way through than one being of good quality at first, then having empty areas or a rushed plot after an arbitrary moment that reveal when develop got rushed to completion.
I find Hobbes calling their little play session stupid amusing in retrospect though. So many of the comics involve him playing Calvinball with Calvin, which is a game where the only rule is rules are made up on the fly, second to second that leaves anyone watching them play it look like absolute nonsense.
"No rules": Game has to have rules, since it's code executed by a machine. There's literally nothing happening that isn't following rules written down (even if they were not as intended they were still left in (bugs/exploits are still rules)).
Games have rules because they're made by living beings. Even animals establish rules, like rats and dogs when they play, where if a dominant animal wins over and over ceaselessly the weaker one will won't play with them anymore since they're sick of never having a chance.
It's actually not. There are plenty of 25+ years old movies that are worth watching today, even thought the technology today is far more advanced. There are 25+ years old games that are worth playing today, and there are games that are not. Trying to find out which are which is by no means pointless.
I'm reminded of my cousins kids who were skeptical of watching Alien when it came my pick of movies and then spent the entire time captivated by it in a way all their modern day choices never did with them as they dicked on their phones.
As much as what Mondblut is true, it is missing a crucial point and it is that which makes sometime timeless.
Hardly anything changed in movies for the past 25 years. Games from 25 years ago are matching Interbellum cinema if you insist on making the comparison. When they just got sound and some even shaken the world with Technicolor.
What of beyond that?
CGI is so universal today special effects that aren't it are unfathomable to younger people who seem to assume anything older that doesn't use it is immediately crap, but amazed when it's convincing in a way most CGI isn't, given that subtle way humans are able to sense when something isn't really there that oddly makes a man in a suit scarier than better made CGI monster.
Also, yes there are Interbellum movies still worth watching today.
It also helps watching them to see that people back then faced the same problems,pondered the same things, had the same fears and imagined things much like ourselves, and just as profound as well as silly.
It's an odd thing that as much as you may try to remind yourself of all of that, seeing people now all dead on a show dealing with such stuff hits you in a way even a book doesn't and is the ultimate gift of film and TV.