Extreme Exorcism [official site] will make you afraid of your own shadow. It's a fast-paced paranormal platformer in which each playthrough becomes increasingly perilous as enemies mimicking your previous victory are overlaid onto the level you're playing. You're fighting against your own ghosts, in the way that racing games often let you compete against your own previous attempt or personal best.
The game is out now and once I'd moved past my initial disappointment that it isn't the rad tale of a skateboarding teenage priest, I jumped in for a swift bout of ghost-smashing. Conceptually, it's fairly simple but well-executed. Survive for even a couple of minutes and you'll be trying to remember exactly what you did on the last couple of playthroughs so that you can predict and avoid the moves of your ghosts.
And then, of course, you start planning ahead, trying to exorcise the existing spirits in the cleanest, simplest fashion possible so as not to create an erratic shadow image. All of your success stories play back at the same time so the area becomes increasingly crowded and eventually you're undone by your own memories - or your inability to process those memories.
"To help send ghosts back to the underworld for good, players are equipped with a lethal arsenal of more than 20 ghost-busting weapons, including swords, guns, grenades, mines, rocket launchers, razor-sharp boomerangs, lightning spells and Kung-Fu moves. Exorcists need all the firepower they can obtain, as they’ll face 50 challenges, a single player story mode and local multiplayer with up-to four players, which includes both Co-op and Deathmatch modes."
There are 10 areas, each with their own in-built hazards, but much of the replay value is probably found in those multiplayer modes. Online play isn't supported so you'll need people in the room with you while you play. I'm all alone at the moment so haven't been able to kill or be killed by the ghosts of my friends.
Extreme Exorcism is available for Windows and Mac from Steam for £8.99.