The 8th Sin by Andrew Sherman

"Opportunity Seldom Knocks, but temptation leans on the doorbell"

A deal with the devil himself is never a good idea, I knew that, but it didn't stop me from signing up for a favor.

When I was too cowardly to talk to the girl I had feelings for, the devil decided to give me a hand,

However the devil works in mysterious and disgusting ways

Now in order to save her soul as well as my own I must beat the devil in a series of trials.

Every night I go to hell now, and face a new horde of demons and a new nightmarish force of evil

Every night a fight, I struggle, and I must find a way to beat the ultimate of all evils without losing my humanity in the process