Or you can have the motion detector light, circle the greeter.
For instance you have a mine field with a bunch of Greeters moveing inbetween mines. Like these are smart Greeters. And there are Muds among the mines. One wrong step BOOM! The greeters go nuts and try to zap you and at the same time set off a huge chain reaction of explosions killing everything.
That would add a rather unique stealth like gameplay in 3D.
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