Is it possible to limit IR led so sensor detects it only if you aim at it?
I repair guns for a system called "Battle Sports".  That employs an infra-red emitter combined with a couple of white LEDs in the gun:



That module is placed at one end of a plastic tube, about 6 inches long. At the other end of the tube is a lens.  The lens is specifically shaped, and placed, so that the light from the module is focused into a roughly parallel beam.  That translates to the white light forming a spot a couple of inches across (used to aim with), and the IR light covering roughly the same area.

The IR is modulated at 56KHz, with a pulsed on/off signal to identify that it's a proper gun that's in use.

The gun also has an IR receiver module on it, as well as a pair of receivers that the user wears on a headband.  These are a simple amplifier / filter arrangement that just returns the pulses without the 56KHz modulation.  They are domed, with a full 360° / 180° range on them, so they can be shot from any angle.