But RE3 had a better story and more detailed environments.
Nemesis could also move between areas where as Mr X couldn't get through most doors.
Given the fact that we're in 2018, I can expect Mr. X to behave like Jack Baker (and be sth more than that). I can quite readily expect him to chase you in the entire Police Station and all the other infrastructures, without giving up so spiritlessly
(by opening doors and breaking through walls if needed).
But, I certainly do expect him to be more. Mr. X and Nemesis have been described in Japanese as 追跡者 (tsuisekisha ; = a pursuer, a chaser).
So how does Mr X become a terrifying B.O.W. that relentlessly hunts you down and tracks you down?
1) By anticipating your next move
2) By setting traps
Let me elaborate on those. How is he going to anticipate your next move (and of course make it appear as if he came out nowhere). The game should take into account the key items that you have in your inventory, in any given moment. You know, in Biohazard games you need key items to solve puzzles and make progress. It's been a hallmark of the series.
Judging by the key items that you have in your inventory, the game might anticipate what kind of puzzles you may solve next. And then randomize the appearance of Mr X.
This is a concept, not in factnovel, the harkens back to Kojima's Metal Gear Solid 1 for PS1. Psycho Mantis would read your memory card trying to find save-slots of other Konami games to show off his psychic abilities and surprise the player.
What about the idea of setting traps and lying in wait? The players, as they play through Biohazard 2 (I mean the old 1998 game), place various key items in the inventory, and then figure out a route to reach the relevant room so as to solve the pertaining puzzle.
Mr. X could take the players by surprise, by blocking/disrupting the route. He might actually destroy the door, the jambs, the lintel and the walls around it, making the room inaccessible and hence forcing the players to contemplate another route. He might in fact destroy various doors forcing the player to a bottleneck (hence the trap) of fighting Mr X himself. Once the player puts him down, he may unveil an item that would help the player overcome all this disruption that was caused.
In any case, I should a expect Mr X to be a beefed up version of Jack Baker, when it comes to behaviour.