... sort of :) Here we got inspired from the prosthetic Nerf gun (There exist also the idea of a mind controlled one .... hmm, looking at the mind flex controller ...). And since the CCCamp this year was a bit dusty, we considered that the world needs also more inclusive water guns:

Using somthing like the EMG sensor (but basically anything else will work) as a trigger on an analogue input an Arduino Nano and a relais connected to a digital output to drive 12V with a "little bit" of current (delivered by 8 AA batteries in row in two 4 AA batterie housings) to control a wiper pump. It will suck the water out of a bottle and soak adversaries through a nozzle at a wristband. The pump is attached with a bunch of hot glue on the bottle cap, otherwise 3D-printed housings and textile strips (reusing lanyard and similar things) are used to attach the parts on belt (Batterie pack with arduino/relais below and the bottle) and arm (EMG sensor and noozle  - but places might vary depending of personal preferences/needs). The also provide a bit of water spray cover, otherwise the good old hot glue is used for encapsulation.

At the beginning we thought that we also need a valve at the bottle to let air in, but at the and, as long as only short pulses are sprayed, the water/air will be sucked back through the pump in between shoots, even preventing/reducing leakage of water through the noozle while not shooting.

Ok, still a little bit far fetched from the original haptic games idea, which turned out to go more into a games for impaired direction), but  actually there exist a paper wher there used water pressure in a sort of old crt-monitor-way as an haptic feedback device ^^.