This is one of my top ten zombies/young people trapped in a mansion movie. I own a copy under its other title : "The House On Tombstone Hill", which if you ask me, I like better than "Dead Dudes In The House".
Two gals and five guys (plus two teenagers who appear in the last 30 minutes) enter a big, old, creepy mansion where soon they find themselves trapped. Doors won't open, windows are unbreakable and soon they begin dying one by one. Some of the murders are off-screen, others you do get to watch happening as the old woman who haunts the mansion uses all sorts of sharp instruments to kill them.
Beware of the Troma DVD release, I bought it thinking it had some kind of special feature like behind the scenes or audio commentary, it doesn't and the quality is NOT good.