I am making efforts to forcibly stop people from leaving.

I saw no effort. You let Olimar escape.

You turn to the room. It is fairly lit, for having only a single window, no doors, and being no larger than the average bedroom. There's a nice brown carpet in the middle of the cobblestone floor. Looking around, you see a painting of a large castle on your left, and on the other side you see a portrait of poison, and straight in front of you is a painting of a woman, presumably a spouse or relation, along with one of an old couple, most likely poison's parents. To your left in the furthermost corner from you there is a vase and a small collection of exotic flowers on an antique table.

This is a map-making site afterall.

You look around, and turning your head funkily you see the Portal you search for. Looking in, you see a dark room, and, deciding that you are BRAVE, and others are COWARDS and PEASANTS, you jump in.

You instantly find yourself in a dimly-lit room, despite the 3 windows in front of you. A small, salt-and-pepper bearded man jumps, and lets out a startled "oh me, I thought it would be one-way." He mutters something, and you feel the space-time continuum close behind you, sealing the portal. The man then steps forward, and disappears into thin air, presumably into another portal. Your assumption is right, and as you look the room slightly lightens as the portal closes. You cannot determine cardinal directions, as you are now indoors.

I'm stuck chained up.

I'll fight Jack for the remote and grant you freedom!

/runs away
I sorta feel bad about locking people up, but if the killer's locked up we win, and if he isn't the three people still locked up are probably gunna be ok if they work together and the killer doesn't find a sniper rifle. We all lose if the killer gets a sniper rifle anyway.

So the gamehost confirms it: Jack is lying. He actually is the killer and wants you all chained up so you're easier to kill. Get him!