Oh yes, I know about Underverse, although I didn't finish watching it with my brother.
I think I knew about Mafiatale, from one of those videos featuring the megalovania song from other sans' aus, but never heard of Mafiafell, excited for it though. Just from the little bit I saw in the IF I know it'll be just as great as this IF.
Don't worry, I already did that. More hot than hellfire, tbh.