I for one would avoid playing any part 2 of anything if I would not know part 1 and especially if said part 2 would tell me to go play part 1 first because of spoilers.
If this is two projects or one project is basically how you design it. If that 2 thingy is standalone playable is different from it being just chapter two and the thing just being the full game with part 1 and 2.