Fast 8 is played with 9 racked balls.
Any 4 stripes, any 4 solids & the 8.
The balls rack in the pattern shown.

      //    0
    0   8   //
      //     0

Same rules apply as standard  8 ball games.
One player has solid balls, the other striped.
Lag for the first break..  Alternate afterwards.
Ball-in-hand for a scratch, or no OB contact.

With BIH, Fast 8 is a good 8 ball run out practice for single players.
After the break, choose the ball group you can most easily run out.
If a break ball pockets choose the other ball group to plan your run.

Look from the 8 ball backwards to plan CB routes to run your balls.
Use the rails to roll your CB into the shot line behind your next OB.

As playing the game of 8 ball, obstacle balls make run outs harder. CMS