Here are what I would call the key ingredients in any casual game:
Rewards
<ul>
<li>Reward early and often</li>
<li>Never punish</li>
</ul>
Progression
<ul>
<li>“Where you are, what is the goal, and where you should go”</li>
<li>Skill-wise and Geographical (in-game geography)</li>
</ul>
Feedback
<ul>
<li>Visual, Aural, Tactile</li>
</ul>
Easy to Learn &amp; Play
<ul>
<li>Gentle difficulty curve</li>
<li>Tutorials</li>
</ul>

Here are what I would call the key ingredients in any casual game:

Rewards
	Reward early and often
	Never punish

Progression
	“Where you are, what is the goal, and where you should go”
	Skill-wise

Key Ingredients in Casual Games