I started making a game like this 7 years ago too. Congrats on your release :)
What I figured was to make there be a cost for using any card, pinned to the number of targets affected, amount of "force" applied, and one or more resources (life, energy, time, space).
Or an equivalent-exchange/extreme-couponing system of some kind. "To destroy the universe, you must first destroy something of equal or greater value." This can deadlock the game though.
After "heat death of the universe" cost too much to play, the workaround ended up being "wait for all other players to die of natural causes" (hadn't implemented time cost yet).
What I figured was to make there be a cost for using any card, pinned to the number of targets affected, amount of "force" applied, and one or more resources (life, energy, time, space).
Or an equivalent-exchange/extreme-couponing system of some kind. "To destroy the universe, you must first destroy something of equal or greater value." This can deadlock the game though.
After "heat death of the universe" cost too much to play, the workaround ended up being "wait for all other players to die of natural causes" (hadn't implemented time cost yet).