Neat!
Never seen an "FPS radar" game before. The white-noise enemies created a good deal of suspense, making me rushing for the beacon a bit.
The fact that there is no background-music actually adds to the immersion, since 99% of the time the player only hears the ticking sound of the scanline.
A possible addition I can think of is a minimap, but not in the casual way, instead, similar to the gameplay.
It could follow the radar itself, so basically it would be the same the player is seeing from the first-person view, but in top-down 2D.
It could provide another perspective to better analyze the surroundings.
As a bit of an extra, the minimap might be circular and show the radar-line as well, however it shouldn't show the beacon, because it would brake the current difficulty and take partially away the unique challenge that comes from the gameplay.