I am working on a concept for now of a PvP game which would be limited to phones and possibly tablets. The game will pair two people for a real-time game. I am not sure if the game is similar to anything in particular, i'm modeling it after two styles - tower defense and card games.
My question is how long should the game take - my gut feeling is it shouldn't be over 5 minutes, perhaps 4 minutes on average?. This would include all rounds, though I am trying to not have rounds. Game won't be fixed to that amount of time, but I need to have an average time in mind to figure out how gameplay should work.