Sword Art Online Alternative Gun Gale Online, Vol. 13 (Light Novel): 5th Squad Jam: Finish (novel)

It's the fifth squad jam and Llen's valued at one hundred million credits. Thrown out into the fog, she's persisted in looking for other participants and finally managed to team up with someone. However, one hour after the start, the outside field starts to crumble until all that's left is a three-kilometer castle.

Llen and friends just barely escape the crumble but Pitohui (?) dies from Shirley's(?) exploding ball. The end is nearing, but there's a newly added special rule.??