You can play Froccer in a number of ways:

The best way is with a friend locally using controllers. You can also play keyboard and controller or both keyboard controls.

You can also play on your own against an "AI" opponent. (Though the "I" is a stretch, so if you can find a human to play against, I'd recommend it).

Controls:

Keyboard 1:

Up/Down/Left/Right: Movement

Right Ctrl: Shoot/Flip

Keyboard 2:

W/A/S/D: Movement

Left Ctrl: Shoot/Flip

Controller 1 & 2:

Left Stick: Movement

X (PS4)/A (Xbox): Shoot/Flip

Built with:

Unity (Engine)
TextMeshPro (Text/UI)
Aseprite (Sprites/Animation)
Bfxr (Sfx)
WolframTones - http://tones.wolfram.com/ (Music)

Font: 

Atari full font by Genshichi Tasui
from https://www.fontspace.com/genshichi-yasui/atari-font 
Licensed as Freeware