When playing with 4 players, the last of the 4 Gods will be placed face-down. It will not be available for this cycle. During the following cycle, you will place this God in the first space, face-up, and shuffle the other 3. Once again, the God placed in 4th place will be face down and will become first God in the following cycle.

If the column reaches or passes the 9th slot, Hades will come into play and replace one of the other Gods!

Mix the god tiles and place them in the usual manner. Then cover the tile of the active God placed just above Apollo, with the Hades tile showing the Hades side.

There is nothing written about placing the God covered by Hades in the following cycle in a special way. So I assume he is shuffled normally with the other Gods and there is a risk, that one God may not appear two cycles in a row. Is this interpretation correct?

The question is relevant for 2/3 players too.

The rules state that:

"Then cover the tile of the active God placed just above Apollo, with the Hades tile showing its “Hades” side."

Since it's the ACTIVE god, it'd be the #3 god in a 4-player game. The face-down god would move up to #1 normally.