Where doing things in the wrong order (which was explained nowhere) would lead to permadeath, or worse, getting stuck with no way to progress and no hint what you missed in a previous area you can't return to.
All I remember from police quest is getting killed or fired for missing a step at a routine traffic stop, or forgetting to check the tire pressure every time you start driving.
In Leisure Suit Larry 1 you straight up get killed without warning if you step onto a street (run over by a car) or into a back alley (mugged and clubbed to death), or take a cab with wine in your inventory (cab driver takes it, drinks it and crashes).
Although I just looked that one up and they have been making new versions of it continuously so I don't know if it really counts as an old 90s game anymore.
One of my friends found his old Gamecube with a copy of 007! So of course we had to have all the boys over to have a little tournament complete with 2 liter sodas and chips and cheap pizza.
Man I forgot how rough around the edges those earlier FPS games really were. They were super bare bones, with janky at best controls, and mediocre hit registration. At least the maps were still good.