(Did a non labor intesive search, didn't see this but maybe it has occurred to someone else. I didn't put this in suggestions cuz its for all games.)

A while back STG stopped deleveling on request, maybe it would work to player and devs advantage to create an elixir that delevels. Seems straightforward to me, purchase and while under its effect every enemy killed has their experience value subtracted from yours. Like the "enable xp anywhere" elixir in pl but backwards.
Wouldn't this work in most games? Maybe theres some way it could be exploitable but I can't think of one being that you would pay for it.
Price of elixir and it's duration would of course be different for each game.
Would it work?