Marked as a spoiler because its a monster from Anomaly. The thing is, these things are not scary, because they don’t have the AI necessary to capitalize on their invisibility. They act like typical raiders, meaning you can place your tough melee guys in a chokepoint, and they’ll come to get their skulls bashed in.
It would probably be better if they instead acted like predatory animals, milling around on the map, and occasionally hunting one of your colonists. If they’d then avoid groups of colonists, while also always attacking in a group themselves, they’d be a truly terrifying monster. Basically, you’d have to hide out in your base, or go out to hunt them. And if you do choose to wait them out, there would be no indication that they’ve left.
I’m just going to say that it depends… My current play through I’ve had two of them. The first I had a really tough time because the first person he took out was my best melee fighter. I had a pacifist, a person with a 3 shooting and one person with a 9 shooting while the rest were on caravan.
I hunted him down as best I could but I didn’t have the necessary people and equipment (wake up) to keep the hunt going
I haven’t seen an sightstealer retreat so far. Are you sure you’re not referring to a revenant, instead?