Schoeny Quest Engine is an engine which makes it easy for you to implement any sort of quest for your game. Quests can also include rewards.
Easy to implement
4 types of quests you can implement:
Item: Check whether a certain number of items have been collected
Boolean: Checks whether a variable has been set to true
Tracker: Check whether a certain number has been reached
Parent: Add other quests to a parent quest
Please visit the documentation page here for instructions on how to implement this engine.