I just got a trial version of Painter X (www.corel.com) is great for making backgrounds for Midnight Mansion. There's a free trial there.

This image I painted in 3 minutes... If I put a bit more effort into it, then it would become a great background for Midnight Mansion.

I first paint-bucketed the background dark blue, then did a few angled strokes of an oil brush with a slightly brighter blue to make that nice Midnight sky. The ground I used a green and a normal brush, and the trees on the ground where just  dark-greenish-brown color. The stars where just white dots, just clicked with a normal brush at a reasonable size.

The moon, was a nice detail. It was like doing the star, (just clicking once, not dragging, with a bigger brush) Then I got a smaller brush and drew the craters and stuff on the moon with a normal grey tone.

Then I got this picture... took me 3 minutes.

Uhh... I think you gotta make an account on the Corel website then you can download it. If you're having trouble, use google to translate the page.