Just a disembodied muzzle flash in the same place on screen. Haven’t got as far as more than one gun yet but the first one is invisible in Vorpx. Everything else in the game so far looks great.
Didn’t recall that anymore, but that’s a side effect of disabling some pseudo 3D HUD element that is supposed to be disabled. The same shaders are used for the weapon, hence that is also invisible. Should still be perfectly playable.