Naomi 1 Main Board, Border Down GD-Rom, and GD-Rom Driver. Border Down is a horizontal-scrolling shooter from G.Rev. There are three difficulties to a level, called "borders", green being the easiest whereas red is the hardest.
The green "border" is the longest variation on a level, but the enemies fire far less frequently. The red "border" is the shortest variation on a level, but the enemies fire at a frantic rate, making it increasingly more difficult to stay alive.
Instead of receiving a set number of lives, a player has the option to start on any "border" at the beginning of the game. Whenever the player dies, a "border down" occurs and the game continues onward on the next hardest difficulty. This puts increasing pressure on the player to stay on the green (easiest) border. The game ends if the player dies while on the red border.