If you've never played the originals, they have about 5-6 ingame hours of length on your first playthrough, it's a relatively short game but the difficulty makes up to it. We know that the games that come out nowadays tend to be much easier and hand holding. So how are they going to make this remake feel a little richer in length? Here are some things they could do:
Add brand new puzzles. Resident Evil 7 had quite a few of those, that game had very well balanced puzzles, not too easy and not too frustrating. We could hope to see a few more in this game.
More cutscenes? Maybe now that they're building the game from scratch they could replace some sections with nice cutscenes.
More playable characters? We can already play as Ada, Claire and Leon. What if they had a whole secret campaign waiting for us in the post game?
Game Modes. The Mercenaries is a very fun minigame, although it doesn't fit this game's mechanics, since the characters are a little more limited than those in Resident Evil 4, 5 and 6. There's still plenty of room for some new fun minigames.
Replayability. The replay value is something most game designers should aim for, having different difficulties shouldn't just increase enemy health and damage. It should change things, less ammo, more enemies, more traps, different puzzles...
I wanted to talk about this because I rarely buy new games that I consider short. When it comes to videogames all I want is to play them for a long time and have a blast, if a game isn't long enough I just won't be happy with my purchase.
What do you think? Will this game be reasonably long or have any replay value in it?