Hopeless The Dark Cave is a game that needs fast reaction to be able to survive from big monsters. There is always a cheat for fast reaction games and it is the slow motion cheat. The question is how you can slow the game in our smartphones or tablets. The answer is "Underclocking". Underclocking reduces your processor speed thus creating a "LAG" and resulting into Slow Motion in the game.
For Android, there are tons of underclock apps. Just search it from google playstore. You don't need root to underclock.
For iPhone, you need to be jailbreak to be able to underclock.