Hmm kicking players one by one may be too slow. How about we set a time limit based on the number of alive players for that round with some maximum time. Any player not in the tower by the time limit is killed.
TimeLimit = (AlivePlayers * 30 seconds)
We continue until there are 2 players left with the ET changing positions every round. The person at the bottom of the stack is the ET. The person above would receive first place and 2 event points. The person above again would receive 1 point.
Numbers may be changed at your discretion.