Sequester

A web game developed by Armor Games, Sequester follows the tale of a young man as he journeys through his twisted dreamscape to help his dead sister cross over to the afterlife. Along the way, he must brave dangerous traps, vengeful spirits, and the eldritch nature of the dream world itself.

Can be played on the Armor Games site here.

Sequester contains the following tropes:

 * Convection Schmonvection: There are lava pits in some levels that only kill the brother on contact.
 * Our Ghosts Are Different: Vengeful ones stalk our protagonist if they see him.
 * Our Souls Are Different
 * World Shapes: Each level in the dream space is shaped like a cube. When you go off one edge of the cube, you appear on the other face that forms that edge. Which leads to...
 * Wrap Around: A rather convoluted example, given the above.
 * Wham Line: