Interesting but kinda useless for airsoft, IMO.
For one, it'll keep shooting people who are hit, meaning it's only a matter of time before your sentry gun encounters an irate player's boot.
Without any kind of AI, you can wave a leafy branch at it from behind cover until it happily expends all it's ammo.
It won't be usable in windy conditions, or it'll be shooting at all the foliage swaying in the breeze. Either that or you'll have to dial sensitivity down enough that it'll become possible to just slowly crawl up to it. (you could make it so it doesn't rely solely on movement by adding FLIR, but I don't think your pockets are that deep).
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