Superfun is dead
The house edge at Superfun 21 is a huge .94% off the top IF you know Superfun strategy, which is different than "normal" blackjack. If you don�t know the strategy, the house edge is even worse. Double deck Superfun is total garbage.
Superfun is beatable with a specialized strategy, a large spread, aggressive playing style and certain, ideal playing conditions. All four factors must be present.
The game is dead. There are not enough games left to make it worth your time to learn to play it. Play blackjack instead.