Basic Information: With nearly all SNK Neo-Geo fighting games, the control pad or joystick has 8-way range other than neutral positioning. As pictured on the above-left picture, there are four buttons used - A (Weak Punch), B (Weak Kick), C (Strong Punch), and D (Strong Kick). Pressing the start button makes your character taunt.

Life Gauge: On the picture at left; the life gauge is the rectangle bar in yellow, which shows how much health/power you have left.

T.O.P Gauge: The sky blue bar in the middle of the life gauge allows you to do your Tactical Offensive Position (TOP) attack with the press of C+D buttons simultaneously. Also, depending on the length and placement (by player choosing), the TOP bar replenishes your health. Aggressive players normally place their TOP attack at full health to quickly defeat opponents while the defensive type will save/place their TOP attack near death.

Just Defended: If you defend a move at the last second, your character will flash blue, and you will gain health (the amount you gain back varies with the move). It is similar to parrying in Street Fighter 3. You can also do this in the air. It has the advantages of life recovery, guard stamina does not increase, and the ability to guard cancel as well. You can Just Defended nearly every attack thrown at you. Just think of it as a block where you gain energy. (-exert taken from GameFAQs.com and James Kuroki)