Mansion Incident (洋館事件,Yōkan jiken?) is the second section of Resident Evil: The Umbrella Chronicles. It is based around the events of the original Resident Evil, set during July 24–25, 1998. The titular levels are unlocked first, with the other four being unlocked later. The following levels are listed in chronological order:
He either makes it to the mansion with the others (Jill's scenario) or his absence is noted by Chris (Chris's scenario)
Richard and Rebecca are found in the library
They are found outside the attic
The Yawn is killed in the library after a single encounter
It is faced in the attic, then the library
Richard is implied to have died offscreen after the Yawn is killed
Richard, depending on the scenario (and version of the game, in certain cases) will either succumb to the venom, or otherwise sacrifice himself against either the Neptune (Chris) or the Yawn (Jill).
Enrico is never found at all, although he is implied by Rebecca to have been killed
Enrico is found in the spider tunnel, and will also be gunned down by Wesker off-screen, although not before strongly implying that S.T.A.R.S. has a traitor within the unit.
Rebecca does not actually witness Wesker's treason at all
In Chris's scenario, should she survive, she ends up learning alongside Chris that Wesker had arranged for the deaths of S.T.A.R.S. and was personally responsible for Enrico's death, with Wesker also proceeding to shoot Rebecca to demonstrate the validity of his treason
Wesker is not encountered at all after his disappearance until they reach the Culture tank room, nor do they learn Wesker's role until that time.
Wesker is encountered at least once between their arrival at the mansion and the aforementioned encounter at the culture tank room (and in the case of the REmake, aids Chris in taking down Lisa Trevor), and Chris and Jill gradually find evidence implicating Wesker as being the mole within Umbrella prior to encountering him at the lab (e.g., Enrico's warning to the two, as well as finding a slide photograph showing Wesker as being among the slides in the projector room of the lab, also Jill warning Chris that Wesker was the traitor when finding her in the cell.).
The self-destruct sequence is activated simultaneously to Wesker getting impaled by the Tyrant
The self-destruct sequence was activated only after the first Tyrant fight, either by Chris, Jill, Rebecca, or Wesker (depending on the scenario)