Back in the day friends were into doing Lazertag with the original retail guns and detectors and they came to me to see what I could do for them. I reverse-engineered a gun, scoped the output to the IR LED in the muzzle and discovered it was a simple short burst of 1kHz, nothing complicated for the target detectors to register.
By the time I had finished they had a couple of hand grenades (push a button, toss it at the Other Guys, three seconds later it fired a burst of 1kHz through a bunch of small IR LEDs peeking through holes of the plastic casing made from laundry detergent globes) and a "knife" (push the handle down against the Other Guy's body close to their target, another short burst of IR from LEDs in the handle shielded from the holder). The best item though was the "bomb on a stick", an omnidirectional radiator on a short pole, just push it round a corner and fire it off. That one emitted for as long as the switch was held down and it had a LOT of IR LEDs. One-shot room clearance FTW.