I think nexus siege would be fun if Events werent a thing.
Sudden Death: flat out disgusting, ruins the mode the most. Takes away any chance of defending and pretty much forces the game into a coinflip win/lose for the sake of early game end timers. Like why force nexus fights? Just let us play it out normally, no need to rush it. Imagine if in ascension a super xeraph spawned that gave 200 points, imagine if in project a max point drone spawned, its just not a cool nor satisfying way to end an intense battle.
Snowball: This one isn't too bad, might be crazier/fun if it was the mark from aram/poro toss but i'm fine with it as is.
Payload: bad, basically gives whoever has priority a free tower.
King of the hill: Bad, this just doesn't work well in league. Especially the random spawn points, making it one sided majority of the time, another "who gets priority" event, and champ pick reliant.
Loot Teemo: bad, pretty much gives who ever's jungle this thing runs in a huge gold advantage and overall event bonus. Even if it spawns in the team's jg thats behind, its not good for comeback as you're just leashing it for the enemy since its defenses are so massive, it'll spawn there and run into the enemy probably, or alternatively it'll spawn on the winning side but they can either actually kill it, or use it to force a fight and kill it+ace the losing side.
Ring of fire: I hate this... TBH I was on pbe and didn't mind it, but in my nexus siege game I was making a smart play for a sneaky herald.. what happens mid way through the herald? Ring of fire forcing me to go fight and get killed because god knows CDs and 75% health isn't enough to survive joining a late fight.
The bonuses you get for completing them are really dumb too.
Nexus blitz's setup is honestly really promising.. there's always lane and jungle interaction with the way things are set up, and the duo jungle + 3 laners offers a lot of versatility for all demographics (support main? Support one of the laners or take smite and assist the jg. Marksmen main? Play it in a role, or even duo with your jg to peel for you, etc).
the map, by design, is great as a permanant substitution mode, maybe not balanced but its actually a fun fiesta.
The events / "experiments" are god awful and put the AR in this urf. Let us test this gamemode without them, and I think I'd play this more often then ARAM.
EDIT: Nexus blitz*