It takes its inspiration from Xevious (being a vertical scroller) and Gradius (from which it borrows its power-up system), and helps to establish Toaplan's trademark style. The game takes place in an Earth-type environment with metallic, land-based enemies; some are mobile armor and others are fortifications embedded in natural terrain.

Certain enemies leave power-up stars upon destruction. Collecting these stars "turns on" an upgrade menu at the bottom of the screen and moves a lit cursor through the list of power-ups described below. If any power-up is lit, but a ship is lost before a power-up could be selected, the star is "carried over" and the Speed block is lit on the next life. Single hits to the unshielded main ship destroy it, and the player loses any accumulated upgrades including Speed. This can make successive lives difficult to keep in the heat of battle.

This game does not support continues with extra credits, and is believed to "loop" endlessly; that is, after the final boss, gameplay resumes at the beginning of the play map but at successively higher difficulty, with enemies shooting faster and more frequently. Also, the score stops increasing when it displays 9,999,990 points, which might be achieved as early as the 15th, 16th, or 17th loops (beginning of 17th verified via MAME emulator).

Taking place in the year 2059 in another galaxy, mankind has colonized an alien planet called Theon after evacuating a previously colonized planet Orac. Five years ago, the colony on Orac was attacked by alien invaders and the war was so intense, the colonists were forced to leave. However, Theon is now under attack by the same alien fleet, but the humans are ready. The player assumes the role of an Allied League of Cosmic Nations (ALCON) fighter pilot in the SW475 star fighter to stop the invaders from taking over Theon.

Power-ups appearing on the upgrade menu are somewhat similar to those in Gradius:

• Speed (upgradeable five times cumulatively)
• Side-Shot (rapid-fire assistant; remains with ship regardless of main weapon unless/until ship is destroyed)
• Shot (short-range, rapid-fire)
• Wing (accessory; increases both the width and the exposure of the craft; improves the power or speed of equipped weapon; upgradeable to three pairs; two external pairs can be used to absorb hits but the whole pair will be lost)
• Bomb (short-range, slow fire, area effect)
• Laser (long-range)
• Homing Missile (releases up to sixteen guided missiles)
• Shield (invulnerability; lasts approx. 25 seconds, or 3 hits, whichever comes first; ends with audible warning)

The major weapons affect the enemies and terrain differently. For example, certain enemy towers can only be destroyed with Laser or Homing Missile; other enemies are destroyed much faster with specific weapons to match. If Bomb or Homing Missile are equipped, certain bonus targets will appear, or parts of the landscape may be destroyed to reveal bonuses. If Laser is active, certain plants in the landscape can be shot repeatedly to 'grow' and earn extra points until they scroll off-screen.

The game was ported to many 8-bit home computers in the European & North American markets.

Slap Fight MD

Slap Fight MD itself is a new game mode featuring featured new levels, graphics, weapons, music, etc, plus a new "smart bomb" feature at the cost of Wing powerups. The music for it was composed by Yuzo Koshiro, which is presented on the title screen.

The original game was also included, but with changes such as configuration for the Shield's timer and an in-game announcer.

Taito Nostalgia 2 version

In Taito Nostalgia 2 for Bandai's Let's! TV play CLASSIC plug and play game system, the original Japanese version and a new Slap Fight Tiger are included.

In Slap Fight Tiger, player controls Heli (from Tiger Heli) instead of Leopard. Laser was changed to fire in 3-way forward. New enemies include the Invaders Army (from Space Invaders).

Uri Cohen of Sega-16 rated the Mega Drive port 8.0.