Player skill

High game depth = Broad skill range + low skill barrier.

How to broaden skill range:

1. Reinvention

From manual phase(operating job), situational phase(reaction) to mental phase(prediction).

2. Elastic challenge

Different levels of success and failure for different levels of players.

3. Training

Help players to pass the skill barrier.

4. Emotional trigger for keeping player stay

Before they pass the skill barrier, maintain players attention through visual or story.

5. Alter the difficulty

From: http://gamerboom.com/archives/59080