Non-level timer base games

Hello Guys,

I am looking to buy addictive unity(iOS, Android) quick to play small games, which should have below constraints,

1) Configurable Countdown timer
2) Player will keep playing the game until the timer becomes 0 (No levels only one level and play for fixed time like 60seconds, 90 seconds)
3) Get the score in the end.

Basically game should be dynamic capable player should get deserved score in the defined time.