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It’s not a skirt. A skirt is what you call a pattern on the ground. This is a highlight with its own color so that the player can see their character better when they are obscured by something. If you press ALT, it becomes even brighter. I just don’t know why they did it this way. Of all the strategy games I’ve played, as far as I remember, to find a lost character or one that is hiding in some shelter, you always have to press a key. Here, any shadow falling on the hero ruins the whole view!