To those unfamiliar with Battle Royale, you may think “What’s stopping them to just leave by magic, flight, or building a boat with those trees?”
 
Well, let just say that those who disobey the rules of the GM usually meet a bloody end.  
By that i mean either their body are rigged with explosive, or they probably had some spell casted on them that does something similar.

luckily it got it’s own tag. That way I can block it (since it’s most likely dark and/or grimdark)

“okay everypony swim off the island except me. there. I win. can we go home now?”  
“that’s cheating. also there are sharks.”  
“we have axes.”

@platypusmac  
It’s not that easy. Obviously some will refuse and try to escape before playing, and there will be consecuences, but not all of this can be said in page 1.

I for one want to see how this goes.

@Background Pony #931F  
For a pegasus? Up. They use clouds as solid walkways after all… Thinking about it, the island is a false problem: a few cloudwalking spells, Twi and Dash as twin engines with other pegasi as backup, and the ponies are all taking a ride home, no problem.  
It’s like saying “You’re stuck on this island” and putting a freakin’ CRUISE SHIP within reach.  
Unless, of course, there is a plot-mandated “no you can’t” rule - kind of silly, since they were doing that kind of stunts BEFORE Twi got her wingy-horned power up.  
That’s kind of different from the Battle Royale kids… THEY were average japanese youngsters, and THESE are magical horsey powerhouses. Kind of like trying to force the JLA’s hand by threatening them with slingshots and water guns. Unless mr. Game Organizer has Tirek and Discord as enforcers, the setting makes no sense.

Pot lid

What stops them from refusing?

@platypusmac  
Plot bombs I’m guessing

@platypusmac  
She doesn’t know where they are. What’s the nearest place of civilization?

What stops Dash from simply leaving and finding help? Wings, y’know…

Tee hee hee,  
On this island, it’s kill or be killed!