Practical Game Design

Confirm risky actions

This may sound like a pure formality but you'd be surprised how many games allow you to break valuable objects and lose hours of progress with an accidental click. Confirm anything that has an irreversible (and potentially negative) outcome for the player. You'd be right to be cautious of constant confirmations getting in the way, but you can easily remove them from strictly positive actions. You can also build in a way to opt out of certain confirmations altogether.