Cowboys and Indians or Soldiers and Armies (or whatever outfit and weapon you happened to own) would always be a good way to vent those boyhood energies. Running and shooting, that’s what it was all about.
Armed with swords and lightsabers, lasers and pistols, and if you had ones with the red gun caps for sound effects (and smell), then even better! The odd argument of whether you were shot or not was quickly forgotten as no one really wants to be lying on the ground with all the action going on, and this was mutually understood.
Water pistols would be the real danger weapon, especially if all you had was a plastic gun which lets face it, does zero damage!!
Into the kitchen for an empty Fairy Liquid bottle would be the answer. Crude, but ideal for long range and always pretty accurate!