My project (Lost Crypts) is a coop Flash dungeon runner, mixing elements of Gauntlet and Rogue. Right now, the core loop works. There's always room for improvement, but the general consensus among play testers is that it is fun.
I talked with someone who is an expert in monetization for these kinds of games and his primary concern was retention and player investment. Right now, the "outer game" loop is relatively weak. You can unlock deeper levels and get on the high score list, but apart from that there's not much to make players come back for the next session.
I have a couple ideas for improving this and I'm looking for suggestions on how to improve them or other ideas:
1.) A mechanism for carrying items to the next life. So if you find a good item, you won't automatically lose it when you die. E.g., if you find a "Last Will" in the dungeon, one of your magic items will pass to your next character.
2.) An achievement progress system. Similar to quests or challenges, players will be able to unlock tiers by completing achievements:
- There will be a set of possible achievements for each tier (e.g., reach level 10, kill 7 monsters in 1 second, etc, find a special item, etc.)
- If a player completes 7 of them, they unlock the tier.
- This will give a permanent reward and their character portrait will show a background indicating the highest tier they've reached and they can start working on the next tier. So every time the player plays, they are potentially making progress.
- The permanent rewards will be in-game useful. For example, the first tier might be the tavern and once unlocked the player always starts with 1 food.
Ideas for other outer loop mechanics? Problems or improvements to these ideas?