I have had a Couple Ideas. I wanted the small quests similar to Desktop Dungeons but here are a couple ideas I have. I am thinking either 2 or 3 and mixing in some 4 for special content:
1. in Game store:
Currency is given as you complete levels and missions and these can be used to purchase new items, heroes, and quests.
2. Unlocks progression
Completing the missions grants you new missions, heroes, and Items
3. Unlock volume
player starts with a pool of missions, heroes, and items. The pools are enlarged as missions are completed. completing a misson with 3 of the 5 heroes adds 2 more heroes. completing 3 of the 5 missions adds more missions.
4. Secret Unlocks
As you play Runes are found. these runes unlock more content.
comments are welcome.