How to better build the aword system? See this article:
In this paper, two commonly contrasted categories of game objectives are juxtaposed: achievements (otherwise known as trophies, medals or badges) and quests (or missions). Recognizing that previous research perceived them as separate and rather broadly understood concepts, the paper follows Mikael Jakobsson (2011) in acknowledging the similarities and overlaps between quests and achievements, which are redefined as umbrella terms describing a range of tasks sharing an objective and a reward. These “objective-based reward systems,” understood additionally as frames for the play experiences, are discussed in relation to their associated level of meaning (Fine, 1983) and attainability (Juul, 2013). Finally, the results are presented in a generalized theoretical model for further study of various objective-based reward systems, going beyond just quests and achievements proper.
Check it here: http://gamestudies.org/2101/articles/waszkiewicz_kominiarczuk