Summary:
When indicating a danger mode use an obvious visual indicator, a color choice may not convey the intended meaning.

Tribly: Art of Theft game screen shot

Problem: Icon color changes to indicate one of two modes, this forces the player to think about which color indicates which mode.

Eye icons

Solution 1: Indicate when the player is in danger of being seen, this is the only mode that is important to the player, no other indication is necessary.

Solution - only show the icon when the player needs to be alerted

Solution 2: Coming soon… This small improvement is part of a series of design iterations I’ll be suggesting to improve the player’s experience in Tribly.

Tribly: The Art Of Theft was designed by Ben ‘Yahtzee’ Croshaw, if you haven’t already heard of Ben, he creates the fabulous Zero Punctuation video game reviews.
Ben’s website is fullyramblomatic.com