The spectacular Lovecraftian game Elder Sign: Omens is only 99 cents right now for Android and iPhone! Your insanity is assured:
Something terrible has begun to awaken within our museum… a something unsatisfied with mere exhibition or human study, writhing with ancient evil and terrible purpose. An entity that must, at all costs, be prevented access to our world. From my studies, I am convinced that such dangers are not new to the human experience. The very fact that humanity survives to this day, I attribute to our forefathers’ success in resisting the tormented realities beyond our own. Among the rarities I have been fortunate enough to uncover, one particular emblem seems significant. A symbol of purported resistive faculty and considerable power. They called it the Elder Sign.
I’ve played this game several times, and I really enjoyed it.