Nice list OP and well done on most of them.
Thanks
I do not really agree slots is good even on PvP,,, what you just described sounds like a manual thing. It is like me playing a single player game and then asking my brother to play after me and seeing who has the higher score;)
Yes, I manually describe "how work PVP slot" from my own perspective but using "Battle Case CSGO Gamling Opened" as the reference of mechanism game. Because I see on that's Battle Case CSGO on Dattdrop when both of player opened the chest and roll the item on the chest. On slot should be like battle case, when the player needs to roll and join the rooms together not separated roll game.
The winners who have a high score at the end of a battle will taking all of the item who already open by other users at the end of the game. That's could be work for PVP Slot Game if some casino wants to bring into the industry, of course the score payout for the roll using "payable payout slot" when battle case open csgo using an item price game. Then the highest balance at the end of the game can take all the prize from fee enter game.
MMORPG sucks too because it is pay to win!
All problems with MMORPG Game XD.