I think only notifications are possible, but not auto-launching an app/game based on a predetermined trigger.
Perhaps a toast notification in Android as a reminder of some sort, but without a tie-in to something like IFTT or another app to automate the handling of the trigger and taking the appropriate response/action, I don't think it's possible for virtually any app/game. Hence why notifications for some apps/games come up when tasks are completed (or w/e timer based thing has completed).