Pick up Linus's pen from the desk, as you will use it later.
Once you have the invitation, you should go left into Charlie Brown's backyard, where he and Snoopy are raking leaves. Play the mini-game where Snoopy blows leaves into the pile. Linus will jump on the pile, then go right to mail his letter. Follow him, and when he realizes his blanket is missing, go back and dig through the leaf pile to get it for him. After he mails the letter, go left again and play the football scene.
When you give him the lemon sucker from Pigpen. He gives you his invitation to the party, and you can get his pen from the desk.
You get the invitation from Linus, who is not planning to attend anyway. When you return the pumpkin for him, he gives you a trick or treat bag, which you give to Pigpen (outside), who gives you a lemon sucker. Take this back to Linus and get his invitation. Also, pick up his pen.
It is on the table after you give Linus the lemon sucker from Pigpen. Linus gives you his invitation to the Halloween Party, and he has just written a letter to the Great Pumpkin. Pick up the pen.
It seems you are mistaken you get the costume and invitation in pumpkin patch island, correct me if im wrong.
There is no pigeon on great pumpkin island.
The pumpkin patch is to the right on Great Pumpkin Island. It was the only area shown in the island preview.
Linus gives you the invitation after you give him the lemon sucker that Pigpen gives you. Roll the pumpkin back to the house and Linus gives you a trick-or-treat bag. Go outside and give it to Pigpen, who gives you a lemon sucker. Give it to Linus and he gives you his invitation. (He'll be in the pumpkin patch all night.)
When you get the bag from Linus for delivering the pumpkin, take it outside and give it to Pigpen (on the sidewalk, right). He will give you a lemon-flavored sucker, which you can give to Linus. He will give you his invitation, which he wasn't going to use anyway.
He is just to the right as you enter the island, in front of Linus and Lucy's house.
Pick up his pen, and go outside, to the far left where Charlie Brown and Snoopy are gathering leaves.
You can get a mask, a sucker, an invitation, a pen, a blanket, and a football. P.S. You have to use most of those for the game tho so you would only keep the mask and the invitation in the end.
There are no buildings or upper rooms on Great Pumpkin Island.