Alright now for the multiplayer scenario. First off I'm going to add something like Memnite to your deck.
Let's say you are playing a 5 man game and each of you is playing a different mono-color (to keep this simple). We'll call all 5 players Blue (you), Red, Green, Black, and White. Obviously the only pact that will win with your Hive Mind trickery is the Pact of Negation as if any one player is able to meet the requirements of the beginning of the upkeep trigger they will not lose and you probably will at the beginning of your upkeep. Obviously you've got some other cards in your deck that gives you some alternatives by not letting them untap so even if they have 3 or more plains in play, they may not be able to pay the upkeep trigger of Intervention Pact.
But we're going to keep this simple. It's your turn 6 again and you were the first player, we'll assume everyone else has 5 basic lands in play that correspond to their color. The player to your right is playing white and during his second main he tapped 4 of his Plains and a Sol Ring to cast Planar Cleansing and nothing on the board had indestructible. So at the beginning of your turn only land is on the board.
Your turn: Untap, Upkeep, Draw, you draw your 6th Island and have Memnite, Hive Mind, and Pact of Negation in already in your hand. In this scenario, assuming the other players work together to ensure you don't get a clean win, you will probably not win, and only one of them (the white player) will lose assuming nobody has any useful instant speed interaction. You also probably will not lose, but if anyone has a counterspell that can target blue, and if combined they can destroy 2 of your lands... before your next turn you will be the only one that loses.
I'll break down how only the white player to your right loses.
First Main you do nothing, skip combat, Second Main:
Play your Island,
Cast Hive Mind, it resolves and comes into play.
Cast Memnite, cast Pact of Negation targeting Memnite on the stack,
Hive Mind triggers and it's ability goes on the stack, all players pass priority.
Hive Mind's ability resolves and starts creating copies of Pact of Negation starting with the active player unless he/she is the one who cast the original spell to be copied (which is the case here) then it goes in play order from the active player (usually to the left) we'll use the order I listed the players above.
A copy of Pact of Negation is created on the stack under Red's control targeting Memnite, as it is created Red can choose a new target for the copy, his only option to switch to is your original Pact of Negation at this time. In his/her situation it doesn't really matter so he leaves it as is.
So from top to bottom our stack now looks like:
Red's copy of Pact of Negation targeting Memnite
Your original Pact of Negation targeting Memnite
Your Memnite
Now Green get's a copy of Pact of Negation on the stack. He can change the target but he thinks about it for a second. If he doesn't, he'll counter Memnite before Red's copy does, making Red's copy fizzle, making Red safe from paying the upkeep trigger. So he leaves the target the same.
So from top to bottom our stack now looks like:
Green's copy of Pact of Negation targeting Memnite
Red's copy of Pact of Negation targeting Memnite
Your original Pact of Negation targeting Memnite
Your Memnite
Black and White see what is happening and White realizes he is screwed in this deal simply by sitting to your right they follow suit.
At the end the stack looks like this:
White's copy of Pact of Negation targeting Memnite
Black's copy of Pact of Negation targeting Memnite
Green's copy of Pact of Negation targeting Memnite
Red's copy of Pact of Negation targeting Memnite
Your original Pact of Negation targeting Memnite
Your Memnite
As long as nobody casts anything else White's copy resolves, Memnite is countered and all other copies and your original fizzle. Only White loses at the beginning of his turn.
You pass turn. Red casts Lava Axe everyone gets a copy and points it at your face. You're copy of Lava Axe will resolve first letting you deal 5 damage to one of them, if that's not enough to kill one of them, you are going to take 20 damage and lose before White does.